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1.	Renlund, Martin, et al. (author) Free N-acetylneuraminic acid in tissues in Salla disease and the enzymes involved in its metabolism 1983 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 130:1, s. 39-45 Journal article (peer-reviewed)abstract Salla disease is a lysosomal storage disorder of unknown etiology, characterized biochemically by increased urinary excretion of N-acetylneuraminic acid. This compound has now been shown to occur in abnormally large amounts in liver and cultured skin fibroblasts from these patients. Quantification of N-acetylneuraminic acid was performed using a new gas-chromatography/mass spectrometric single-ion method which is sensitive and specific. No abnormalities in the activity of several enzymes involved in sialic acid metabolism (N-acetylneuraminate:pyruvate lyase, neuraminidase, CMP-N-acetylneuraminate N-acylneuraminohydrolase and CTP:N-acyl-neuraminate cytidylyltransferase) were demonstrable. A possible explanation for the defect is a malfunctioning active transport of N-acetylneuraminic acid across the lysosomal membrane.
2.	Elbing, Karin, 1974, et al. (author) Transcriptional responses to glucose at different glycolytic rates in Saccharomyces cerevisiae 2004 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 271:23-24, s. 4855-4864 Journal article (peer-reviewed)abstract The addition of glucose to Saccharomyces cerevisiae cells causes reprogramming of gene expression. Glucose is sensed by membrane receptors as well as (so far elusive) intracellular sensing mechanisms. The availability of four yeast strains that display different hexose uptake capacities allowed us to study glucose-induced effects at different glycolytic rates. Rapid glucose responses were observed in all strains able to take up glucose, consistent with intracellular sensing. The degree of long-term responses, however, clearly correlated with the glycolytic rate: glucose-stimulated expression of genes encoding enzymes of the lower part of glycolysis showed an almost linear correlation with the glycolytic rate, while expression levels of genes encoding gluconeogenic enzymes and invertase (SUC2) showed an inverse correlation. Glucose control of SUC2 expression is mediated by the Snf1-Mig1 pathway. Mig1 dephosphorylation upon glucose addition is known to lead to repression of target genes. Mig1 was initially dephosphorylated upon glucose addition in all strains able to take up glucose, but remained dephosphorylated only at high glycolytic rates. Remarkably, transient Mig1-dephosphorylation was accompanied by the repression of SUC2 expression at high glycolytic rates, but stimulated SUC2 expression at low glycolytic rates. This suggests that Mig1-mediated repression can be overruled by factors mediating induction via a low glucose signal. At low and moderate glycolytic rates, Mig1 was partly dephosphorylated both in the presence of phosphorylated, active Snf1, and unphosphorylated, inactive Snf1, indicating that Mig1 was actively phosphorylated and dephosphorylated simultaneously, suggesting independent control of both processes. Taken together, it appears that glucose addition affects the expression of SUC2 as well as Mig1 activity by both Snf1-dependent and -independent mechanisms that can now be dissected and resolved as early and late/sustained responses.
3.	Eriksson, Torny, et al. (author) Heterogeneity of homologously expressed Hypocrea jecorina (Trichoderma reesei) Cel7B catalytic module 2004 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 271:7, s. 1266-1276 Journal article (peer-reviewed)abstract The catalytic module of Hypocrea jecorina (previously Trichoderma reesei) Cel7B was homologously expressed by transformation of strain QM9414. Post-translational modifications in purified Cel7B preparations were analysed by enzymatic digestions, high performance chromatography, mass spectrometry and site-directed mutagenesis. Of the five potential sites found in the wild-type enzyme, only Asn56 and Asn182 were found to be N-glycosylated. GlcNAc(2)Man(5) was identified as the predominant N-glycan, although lesser amounts of GlcNAc(2)Man(7) and glycans carrying a mannophosphodiester bond were also detected. Repartition of neutral and charged glycan structures over the two glycosylation sites mainly accounts for the observed microheterogeneity of the protein. However, partial deamidation of Asn259 and a partially occupied O-glycosylation site give rise to further complexity in enzyme preparations.
4.	Florén, Claes-Henrik, et al. (author) Effects of fatty acid unsaturation on chylomicron metabolism in normal and hepatectomized rats 1977 In: Eur J Biochem. - : Wiley. - 0014-2956. ; 77:1, s. 23-30 Journal article (peer-reviewed)abstract 1. Hepatectomized rats were injected intravenously with doubly labelled ([14C]linoleic acid and [3H]palmitic acid) thoracic duct lymphs from rats fed cream, triolein or corn oil. The disappearance of the radioactive fatty acids of different molecular triacylglycerol species and of phospholipids from plasma was studied.2. 73–93% of the injected triacylglycerols had been cleared from plasma within 15 min. At all stages of lipolysis the 3H/14C ratio of the plasma triacylglycerol was the same as in the injected material. If the cream chyle had been cooled to 4 °C before use there was, however, an enrichment of [3H]palmitic acid and of fully saturated triacylglycerols in the remnant particles formed.3. Only 38–50% of the radioactive chyle phosphatidylcholine was eliminated from plasma in 30 min. At this time most of the remaining phosphatidylcholine was, however, in other lipo‐protein classes than the chylomicron remnants.4. Also in intact rats data were obtained, indicating that the major portion of chylomicron phospholipids is transferred to other serum lipoproteins by exchange or net movement rather than being hydrolysed in the 1‐position by lipoprotein lipase or taken up intact by the liver.5. More of both the labelled fatty acids appeared in liver triacylglycerols in experiments with cream chyle than in experiments with corn oil chyle. Data were obtained suggesting that this may be due to a higher uptake of intact triacylglycerol as remnant particles.6. When linoleic acid is fed as a tracer dose in cream, a high proportion (16–36%) is incorporated into chyle phospholipids.
5.	GOLOLOBOV, Mikhail Y., et al. (author) The second nucleophile molecule binds to the acyl‐enzyme–nucleophile complex in α‐chymotrypsin catalysis : Kinetic evidence for the interaction 1993 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 217:3, s. 955-963 Journal article (peer-reviewed)abstract α‐Chymotrypsin‐catalyzed acyl tranfer was studied using three acyl‐group donors (Mal‐l‐Ala‐l‐Ala‐l‐PheOMe, Bz‐l‐TyrOEt and Ac‐l‐TrpOEt; Mal, maleyl; Bz, benzoyl; OMe, methyl ester; OEt, ethyl ester) and a series of amino‐acid amides. Most of the reactions studied can be described by the simplest kinetic model without the nucleophile binding to the acyl‐enzyme. The α‐chymotrypsin‐catalyzed transfer of the Mal‐l‐Ala‐l‐Ala‐l‐Phe group to the amides of L‐Phe and L‐Tyr showed a linear dependence of the partition constant, p, on the nucleophile concentration which can be interpreted by the hydrolysis of the acyl‐enzyme–nucleophile complex. The α‐chymotrypsin‐catalyzed transfer of the Bz‐l‐Tyr and Ac‐l‐Trp groups to several amino‐acid amides showed unusual behavior which can be interpreted by the kinetic model involving formation of a complex of the acyl‐enzyme with two nucleophile molecules. These observations can explain the conflicting conclusions concerning the kinetics of α‐chymotrypsin‐catalyzed acyl transfer evident in previous studies.
6.	Kang, J, et al. (author) Total chemical synthesis and NMR characterization of the glycopeptide tx5a, a heavily post-translationally modified conotoxin, reveals that the glycan structure is alpha-D-Gal-(1 -> 3)-alpha-D-GalNAc 2004 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 271:23-24, s. 4939-4949 Journal article (peer-reviewed)abstract The 13-amino acid glycopeptide tx5a (Gla-Cys-Cys-Gla-Asp-Gly-Trp-Cys-Cys-Thr-Ala-Ala-Hyp-OH, where Trp* = 6-bromotryptophan and Thr* = Gal-GalNAc-threonine), isolated from Conus textile, causes hyperactivity and spasticity when injected intracerebral ventricularly into mice. It contains nine post-translationally modified residues: four cysteine residues, two gamma-carboxyglutamic acid residues, and one residue each of 6-bromotryptophan, 4-trans-hydroxyproline and glycosylated threonine. The chemical nature of each of these has been determined with the exception of the glycan linkage pattern on threonine and the stereochemistry of the 6-bromotryptophan residue. Previous investigations have demonstrated that tx5a contains a disaccharide composed of N-acetylgalactosamine (GalNAc) and galactose (Gal), but the interresidue linkage was not characterized. We hypothesized that tx5a contained the T-antigen, beta-D-Gal-(1-->3)-alpha-D-GalNAc, one of the most common O-linked glycan structures, identified previously in another Conus glycopeptide, contalukin-G. We therefore utilized the peracetylated form of this glycan attached to Fmoc-threonine in an attempted synthesis. While the result-ing synthetic peptide (Gla-Cys-Cys-Gla-Asp-Gly-Trp-Cys-Cys-Thr-Ala-Ala-Hyp-OH, where Trp* =6-bromotryptophan and Thr* = beta-D-Gal-(1-->3)-alpha-D-GalNAc-threonine) and the native peptide had almost identical mass spectra, a comparison of their RP-HPLC chromatograms suggested that the two forms were not identical. Two-dimensional H-1 homonuclear and C-13-H-1 heteronuclear NMR spectroscopy of native tx5a isolated from Conus textile was then used to determine that the glycan present on tx5a indeed is not the aforementioned T-antigen, but rather alpha-D-Gal-(1-->3)-alpha-D-GalNAc.
7.	Kvassman, Jan, et al. (author) Mechanism of glyceraldehyde‐3‐phosphate transfer from aldolase to glyceraldehyde‐3‐phosphate dehydrogenase 1988 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 172:2, s. 427-431 Journal article (peer-reviewed)abstract The catalytic interaction of glyceraldehyde‐3‐phosphate dehydrogenase with glyceraldehydes‐3‐phosphate has been examined by transient‐state kinetic methods. The results confirm previous reports that the apparent Km for oxidative phosphorylation of glyceraldehydes‐3‐phosphate decreases at least 50‐fold when the substrate is generated in a coupled reaction system through the action of aldolase on fructose 1,6‐bisphosphate, but lend no support to the proposal that glyceraldehydes 3‐phosphate is directly transferred between the two enzymes without prior release to the reaction medium. A theoretical analysis is presented which shows that the kinetic behaviour of the coupled two‐enzyme system is compatible in all respects tested with a free‐diffusion mechanism for the transfer of glyceraldehydes 3‐phosphate from the producing enzyme to the consuming one.
8.	Larsson, Karin M., et al. (author) Activity and stability of horse‐liver alcohol dehydrogenase in sodium dioctylsulfosuccinate/cyclohexane reverse micelles 1987 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 166:1, s. 157-161 Journal article (peer-reviewed)abstract Horse liver alcohol dehydrogenase (EC 1.1.1.1) solubilized in sodium dioctylsulfosuccinate (AOT)/cyclohexane reverse micelles was used for the oxidation of ethanol and reduction of cyclohexanone in a coupled substrate/coenzyme recycling system. The activity of the enzyme was studied as a function of pH and water content. The enzyme was optimally active in microemulsions prepared with buffer of pH around 8. An increase in enzymatic activity was observed as a function of increasing water content. The Km values for the substrates were calculated based on the total reaction volume. The apparent Km for ethanol in reverse micelles was about eight times lower as compared to that in buffer solution, whereas the Km for cyclohexanone was almost unaltered. Storage and operational stability were investigated. It was found that the specific activity of the alcohol dehydrogenase operating in reverse micellar solution was good for at least two weeks. The steroid eticholan‐3ß‐ol‐17‐one was also used as a substrate. In this case the reaction rate was approximately five times higher in a reverse micellar solution than in buffer.
9.	Malm, Johan, et al. (author) Isolation and characterization of the major gel proteins in human semen, semenogelin I and semenogelin II 1996 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 238:1, s. 48-53 Journal article (peer-reviewed)abstract Semenogelin I and semenogelin II constitute the major gel-forming proteins in human semen. The gel proteins were rapidly solubilized and separated from spermatozoa in ejaculates collected at pH 9.7 in buffer containing 4 mol/l urea and dithiothreitol. This protected the semenogelins from proteolytic degradation by prostate-specific antigen, and allowed their isolation by affinity chromatograph:g on heparin-sepharose. Semenogelins I and II were almost selectively retained and eluted partially separated in 0.25 mol/l NaCl. Further purification was achieved by chromatography on Superose. Approximately 10-20 mg semenogelin I and 2-5 mg semenogelin II were recovered from each sample with a purity exceeding 95% as judged by SDS/PAGE. The molecular mass of semenogelin I (49,958 Da) and the major form of semenogelin II (63,539 Da) measured by mass spectrometry was consistent with the reported cDNA data. The occurrence of a second, larger form of semenogelin II was due to asparagine-linked glycosylation. The amino-termini of the purified proteins were blocked, but digestion with pyroglutamate aminopeptidase enabled the identification of amino-terminal sequences consistent with the reported cDNA data. The amino acid compositions of the purified proteins were also consistent with those derived from cDNA data. The absorption coefficients (280 nm, 1%, 1 cm) for semenoaelins I and II. were 5.5 and 5.4, respectively, and the isoelectric point was above pH 9.5 for both proteins.
10.	Martinez Arias, Wilma, et al. (author) Mechanism of NADH Transfer between Alcohol Dehydrogenase and Glyceraldehyde-3-Phosphate Dehydrogenase 1997 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 250:1, s. 158-162 Journal article (peer-reviewed)abstract Steady-state and transient-state kinetic experiments have been performed to test the proposal that there is a direct (channelled) transfer of NADH from glyceraldehyde-3-phosphate dehydrogenase to alcohol dehydrogenase. The results lend no support to this proposal, but can be best explained in terms of a free-diffusion mechanism for NADH transfer between the two enzymes.
11.	Martinez Arias, Wilma, et al. (author) Transient-State Kinetic Evidence Against a Channelled Transfer of Glyceraldehyde 3-Phosphate from Aldolase to Glyceraldehyde-3-Phosphate Dehydrogenase 1996 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 239:3, s. 675-678 Journal article (peer-reviewed)abstract Theoretical and experimental evidence is presented which leads to a rejection of the proposal that the transient-state kinetics of the coupled two-enzyme reaction involving aldolase and glyceraldehyde-3-phosphate dehydrogenase are indicative of a channelled transfer of glyceraldehyde 3-phosphate from the producing enzyme to the consuming one.
12.	Morimatsu, K., et al. (author) Roles of Tyr103 and Tyr264 in the regulation of RecA-DNA interactions by nucleotide cofactors 1996 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 240:1, s. 91-97 Journal article (peer-reviewed)abstract The DNA-binding mode of the RecA protein, in particular its dependence on nucleotide cofactor, has been investigated by monitoring the fluorescence and linear-dichroism signals of a tryptophan residue inserted in the RecA to replace tyrosine at position 103 or 264. These residues are important for cofactor and DNA binding, as evidenced from their fluorescence changes upon binding of cofactor and DNA [Morimatsu, K., Horii, T, & Takahashi, M. (1995) Eur. J. Biochem. 228, 779-785]. The substitution of these residues with tryptophan does not affect the structure or biological function of the complex and can therefore be exploited to gain structural information in terms of the orientation and environment of the inserted reporter chromophore. The fluorescence change upon formation of the ternary cofactor . RecA . DNA complex was much smaller than the sum of the changes induced by cofactor or DNA alone, This difference indicates that the cofactor and DNA interact with RecA via common components. The fluorescence change caused by DNA in the presence of cofactor was almost independent of the base composition of DNA, in contrast to the interaction in the absence of cofactor. Hence, the contact mode between the selected residues and DNA in the complex may depend significantly on the cofactor, Linear-dichroism measurements indicate that the cofactor does not markedly alter the organization of RecA filament. Linear dichroism shows that neither the aromatic moiety of residue 103 nor that of residue 264 is intercalated between the DNA bases. The textural changes reported for the helical pitch and contour length of RecA fiber upon interaction with cofactor and DNA may derive from a subtle change in orientation of the RecA subunits in the filament.
13.	Nicolaes, GAF, et al. (author) Altered inactivation pathway of factor Va by activated protein C in the presence of heparin 2004 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 271:13, s. 2724-2736 Journal article (peer-reviewed)abstract Inactivation of factor Va (FVa) by activated protein C (APC) is a predominant mechanism in the down-regulation of thrombin generation. In normal FVa, APC-mediated inactivation occurs after cleavage at Arg306 (with corresponding rate constant k'(306)) or after cleavage at Arg506 (k(506)) and subsequent cleavage at Arg306 (k(306)). We have studied the influence of heparin on APC-catalyzed FVa inactivation by kinetic analysis of the time courses of inactivation. Peptide bond cleavage was identified by Western blotting using FV-specific antibodies. In normal FVa, unfractionated heparin (UFH) was found to inhibit cleavage at Arg506 in a dose-dependent manner. Maximal inhibition of k(506) by UFH was 12-fold, with the secondary cleavage at Arg306 (k(306)) being virtually unaffected. In contrast, UFH stimulated the initial cleavage at Arg306 (k'(306)) two- to threefold. Low molecular weight heparin (Fragmin(R)) had the same effects on the rate constants of FVa inactivation as UFH, but pentasaccharide did not inhibit FVa inactivation. Analysis of these data in the context of the 3D structures of APC and FVa and of simulated APC-heparin and FVa-APC complexes suggests that the heparin-binding loops 37 and 70 in APC complement electronegative areas surrounding the Arg506 site, with additional contributions from APC loop 148. Fewer contacts are observed between APC and the region around the Arg306 site in FVa. The modeling and experimental data suggest that heparin, when bound to APC, prevents optimal docking of APC at Arg506 and promotes association between FVa and APC at position Arg306.
14.	Pettersson, Gösta, et al. (author) A rapid‐equilibrium model for the control of the Calvin photosynthesis cycle by cytosolic orthophosphate 1987 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 169:2, s. 423-429 Journal article (peer-reviewed)abstract A simple model based on rapid‐equilibrium assumptions is derived which relates the steady‐state activity of the Calvin cycle for photosynthetic carbohydrate formation in C3 plants to the kinetic properties of a single cycle enzyme (fructose bisphosphatase) and of the phosphate translocator which accounts for the export of photosynthate from the chloroplast. Depending on the kinetic interplay of these two catalysts, the model system may exhibit a single or two distinct modes of steady‐state operation, or may be unable to reach a steady state. The predictions of the model are analysed with regard to the effect of external orthophosphate on the steady‐state rate of photosynthesis in isolated chloroplasts under conditions of saturating light and CO2. Due to the possible existence of two distinct steady states, the model may account for the stimulatory as well as the inhibitory effects of external phosphate observed in experiments with intact chloroplasts. Stability arguments indicate, however, that only the steady‐state case corresponding to phosphate inhibition of the rate of photosynthesis could be of physiological interest. It is concluded that chloroplasts under physiological conditions most likely operate in a high‐velocity steady state characterized by a negative Calvin cycle flux control coefficient for the phosphate translocator. This means that any factor enhancing the export capacity of the phosphate translocator can be anticipated to decrease the actual steady‐state rate of photosynthate export due to a decreased steady‐state rate of cyelic photosynthate production.
15.	Pettersson, Gösta, et al. (author) Dependence of the Calvin cycle activity on kinetic parameters for the interaction of non‐equilibrium cycle enzymes with their substrates 1989 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 186:3, s. 683-687 Journal article (peer-reviewed)abstract Kinetic model studies and control analyses of the Calvin photosynthesis cycle have been performed to characterize the dependence of the cycle activity on maximum velocities and Kmvalues for the interaction of the non‐equilibrium cycle enzymes and ATP synthetase with their substrates under conditions of light and carbon dioxide saturation. The results show that Km values have no major influence on the cycle activity at optimal concentrations of external orthophosphate. The maximum cycle activity is controlled mainly by the catalytic capacities of ATP synthetase and sedoheptulose‐bisphosphatase, and is close to the maximum cycle flux that can be supported by these two enzymes.
16.	Pettersson, Gösta, et al. (author) Metabolites controlling the rate of starch synthesis in the chloroplast of C3 plants 1989 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 179:1, s. 169-172 Journal article (peer-reviewed)abstract The extent to which different stromal metabolites affecting ADPglucose pyrophosphorylase control the rate of photosynthetic starch production in the chloroplast of C3 plants has been examined by kinetic model studies. The results indicate that ATP, glucose 1‐phosphate, 3‐phosphoglycerate, fructose 6‐phosphate, and orthophosphate may provide significant contributions to the starch synthesis rate changes induced by variation of the external concentration of orthophosphate, the detailed control situation being dependent on the actual concentration of the external metabolite.
17.	Pettersson, Gösta, et al. (author) On the regulatory significance of inhibitors acting on non‐equilibrium enzymes in the Calvin photosynthesis cycle 1989 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 182:2, s. 373-377 Journal article (peer-reviewed)abstract Control analyses and kinetic model studies have been performed in order to obtain quantitative information on the regulatory significance of 12 experimentally well‐documented inhibitory interactions of Calvin cycle intermediates with the four non‐equilibrium cycle enzymes. Evidence is presented to show that none of these interactions contributes significantly to the cycle flux control over the range of external orthophosphate concentrations where the reaction cycle shows close to optimal activity. Contrary to what has been generally supposed, the examined inhibitions appear to be of little interest for our understanding of the biological regulation of the Calvin photosynthesis cycle under conditions of light and carbon dioxide saturation.
18.	Rasmusson, A. G., et al. (author) Effect of calcium ions and inhibitors on internal NAD(P)H dehydrogenases in plant mitochondria 1991 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 202:2, s. 617-623 Journal article (peer-reviewed)abstract Both the external oxidation of NADH and NADPH in intact potato (Solanum tuberosum L. cv. Bintje) tuber mitochondria and the rotenone-insensitive internal oxidation of NADPH by inside-out submitochondrial particles were dependent on Ca2+. The stimulation was not due to increased permeability of the inner mitochondrial membrane. Neither the membrane potential nor the latencies of NAD+-dependent and NADP+-dependent malate dehydrogenases were affected by the addition of Ca2+. The pH dependence and kinetics of Ca2+-dependent NADPH oxidation by inside-out submitochondrial particles were studied using three different electron acceptors: O2, duroquinone and ferricyanide. Ca2+ increased the activity with all acceptors with a maximum at neutral pH and an additional minor peak at pH 5.8 with O2 and duroquinone. Without Ca2+, the activity was maximal around pH 6. The K(m) for NADPH was decreased fourfold with ferricyanide and duroquinone, and twofold with O2 as acceptor, upon addition of Ca2+. The V(max) was not changed with ferricyanide as acceptor, but increased twofold with both duroquinone and O2. Half-maximal stimulation of the NADPH oxidation was found at 3 μM free Ca2+ with both O2 and duroquinone as acceptors. This is the first report of a membrane-bound enzyme inside the inner mitochondrial membrane which is directly dependent on micromolar concentrations of Ca2+. Mersalyl and dicumarol, two potent inhibitors of the external NADH dehydrogenase in plant mitochondria, were found to inhibit internal rotenone-insensitive NAD(P)H oxidation, at the same concentrations and in manners very similar to their effects on the external NAD(P)H oxidation.
19.	RESLOW, Mats, et al. (author) On the importance of the support material for bioorganic synthesis : Influence of water partition between solvent, enzyme and solid support in water‐poor reaction media 1988 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 172:3, s. 573-578 Journal article (peer-reviewed)abstract α‐Chymotrypsin was adsorbed on solid support materials and the catalytic activity of the preparations in organic solvents was studied. The activity was highly dependent on the nature of the support material and on the amount of water present in the reaction mixture. There appears to be competition for the water in the system between the enzyme, the support material and the solvent. The support materials were characterized by measuring their ability to absorb water from water‐saturated diisopropyl ether. For the quotient: (amount of water on the support)/(amount of water in the solvent) in the model system the term aquaphilicity was proposed. The activity of adsorbed chymotrypsin in diisopropyl ether decreased with increasing aquaphilicity of the support material. The same trend was observed when the activity of horse liver alcohol dehydrogenase adsorbed on different supports was measured in diisopropyl ether.
20.	Rosén, Stefan, et al. (author) A multispecific saline-soluble lectin from the parasitic fungus Arthrobotrys oligospora. Similarities in the binding specificities compared with a lectin from the mushroom agaricus bisporus. 1996 In: European journal of biochemistry / FEBS. - : Wiley. - 0014-2956 .- 1432-1033. ; 238:3, s. 830-7 Journal article (peer-reviewed)abstract Several fungi can express high levels of saline-soluble and low-molecular-mass lectins that bind to glycoproteins such as fetuin and different mucins but not bind to any monosaccharides. In this paper, we report the binding specificities of such a lectin (designated AOL) isolated from the nematophagous fungus Arthrobotrys oligospora. The results show that AOL is a multispecific lectin that interacts with the following ligands: (a) Several sulfated glycoconjugates including sulfatide, dextran sulfate, and fucoidan. The specificity of this binding was indicated by experiments showing that none of the tested neutral- and sialic-acid-containing glycolipids, chondroitin sulfates B and C, heparin, and polyvinyl sulfate bound to AOL; (b) Phosphatidic acid and phospatidylglycerol, two out of several tested phospholipids. (c) N-linked and O-linked sugar chains bound to intact fetuin. The involvement of such sugar structures was demonstrated by analyzing the binding of AOL to chemically deglycosylated (trifluoromethanesulfonic acid) fetuin. Treating fetuin with O-glycosidase and N-glycosidase indicated that AOL bound to Gal beta GaLNAc alpha-Ser/Thr and to some N-linked complex sugars, respectively. Further assays demonstrated that AOL could interact with several other glycoproteins containing O-linked and/or N-linked sugar chains. The observations that AOL did not bind to free N-linked sugars isolated from fetuin, or to fetuin treated with trypsin or pronase, or to any of the tested neoglycoproteins and glycolipids with neutral- or sialic acid-containing sugars, indicated that the sugar chains need to be bound to an intact peptide backbone to interact with AOL. We have recently shown that the deduced primary structure of AOL has a high similarity to the sequence of a saline-soluble lectin isolated from the mushroom Agaricus bisporus (ABL) (Rosén, S., Kata, M., Persson, Y., Lipniunas, P. H., Wikström, M., van den Hondel, C. A. M. J. J., van den Brink, J. M., Rask, L., Hedén L.-O. and Tunlid, A., see companion paper). It is well known that ABL binds to Gal beta 3GaLNAc alpha-Ser/Thr, and in this paper we demonstrate that ABL binds to sulfatide, phosphatidic acid, phospatidylglycerol, and possibly also to the same N-linked complex sugars as AOL. The above data indicate that AOL and ABL are members of a novel family of fungal lectins sharing similar primary structure and binding properties.
21.	Rosén, Stefan, et al. (author) Molecular characterization of a saline-soluble lectin from a parasitic fungus : Extensive sequence similarities between fungal lectins 1996 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 238:3, s. 822-829 Journal article (peer-reviewed)abstract It has been proposed that the interactions between several parasite and pathogenic fungi and their hosts are mediated by soluble lectins present in the fungus. We have cloned and analyzed a gene encoding such a lectin (AOL) from the nematophagous fungus Arthrobotrys oligospora (deuteromycete). The deduced primary structure of the AOL gene displayed an extensive similarity (identity 46.3%) to that of a gene encoding a lectin (ABL) recently isolated from the mushroom Agaricus bisporus (basidiomycete), but not to any other fungal, microbial, plant, or animal lectins. The similarities between AOL and ABL were further demonstrated by the observation that an antibody specific for AOL cross-reacted with ABL. Together with data showing that AOL has a binding specificity that is similar to that of ABL [Rosen, S., Bergstrom, J., Karlsson, K.-A., and Tunlid, A. (1996) Eur. J. Biochem. 238, 830-837], these results indicate that AOL and ABL are members of a novel family of saline- soluble lectins present in fungi. Southern blots indicated that there is only one AOL gene in the genome encoding a subunit (monomer) of the lectin. The primary structure of AOL did not show the presence of a typical N-terminal signal sequence. Comparison of the deduced primary structure with the molecular mass of AOL as determined by electrospray mass spectrometry (16153 Da), indicated that AOL has an acetylated N-terminal but no other post- translational modifications, and that a minor isoform is formed by deamidation. Circular dichroism (CD) spectroscopy suggested that the secondary structure of AOl contains 34% β-sheets, 21% α-helix, and 45% turns and coils.
22.	Ryde-Pettersson, Ulf (author) A theoretical treatment of damped oscillations in the transient state kinetics of single‐enzyme reactions 1989 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 186:1-2, s. 145-148 Journal article (peer-reviewed)abstract An extension of the available kinetic theory for reactions in the transient state is presented which establishes that single‐enzyme reactions may exhibit damped oscillations under the conditions of standard kinetic experiments performed by stopped‐flow techniques. Such oscillations may occur for reasonable magnitudes of rate constants in the enzymic reaction mechanism and at physiological concentrations of enzyme and substrate. In the simplest reaction systems, the oscillations will be strongly damped and lead to progress curves resembling those of a reaction governed by standard exponential transients; statistical regression methods may then have to be applied for their detection and characterization. The observation that single‐enzyme reactions may exhibit oscillatory behaviour points to a previously unrecognized possible source of the damped oscillations observed in metabolic systems such as the pathways of glycolysis or photosynthesis.
23.	Ryde-Pettersson, Ulf (author) Identification of possible two‐reactant sources of oscillations in the Calvin photosynthesis cycle and ancillary pathways 1991 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 198:3, s. 613-619 Journal article (peer-reviewed)abstract A systematic search for possible sources of experimentally observed oscillations in the photosynthetic reaction system has been performed by application of recent theoretical results characterizing the transient‐state rate behaviour of metabolic reactions involving two independent concentration variables. All subsystems involving two independent reactants in metabolically fundamental parts of the Calvin cycle and the ancillary pathways of starch and sucrose synthesis have been examined in order to decide on basis of their kinetic and stoichiometric structure whether or not they may trigger oscillations. The results show that no less than 20 possible oscillators can be identified in the examined reaction system, only three of which have been previously considered as potential sources of experimentally observed oscillations. This illustrates the superiority of the method now applied over those previously used to identify possible two‐reactant sources of metabolic oscillations and indicates that there should be no difficulty in complex metabolic pathways to point to a multitude of interactions that may trigger an oscillatory rate behaviour of the system.
24.	Ryde-Pettersson, Ulf (author) On the mechanistic origin of damped oscillations in biochemical reaction systems 1990 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 194:2, s. 431-436 Journal article (peer-reviewed)abstract A generalized reaction scheme for the kinetic interaction of two reactants in a metabolic pathway has been examined in order to establish what minimal mechanistic patterns are required to support a damped oscillatory transient‐state kinetic behaviour of such a two‐component system when operating near a steady state. All potentially oscillating sub‐systems inherent in this scheme are listed and briefly characterized. The list includes several mechanistic patterns that may be frequently encountered in biological system (e.g. involving feedback inhibition, feed‐forward activation, substrate inhibition or product activation), but also draw attention to some hitherto unforeseen mechanisms by which the kinetic interaction of two metabolites may trigger damped oscillations. The results can be used to identify possible sources of oscillations in metabolic pathways without detailed knowledge about the explicit rate equations that apply.
25.	Schmidtchen, Artur, et al. (author) Analysis of glycosaminoglycan chains from different proteoglycan populations in human embryonic skin fibroblasts 1992 In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 208:2, s. 537-546 Journal article (peer-reviewed)abstract 1. The structure of chondroitin/dermatan and heparan-sulphate chains from various proteoglycan populations derived from cultured human skin fibroblasts have been examined. Confluent cell cultures were biosynthetically labelled with [3H]-glucosamine and 35SO4(2-), and proteoglycans were purified according to buoyant density, size and charge density [Schmidtchen, A., Carlstedt, I., Malmstrom, A. & Fransson, L.-A. (1990) Biochem. J. 265, 289-300]. Some proteoglycan fractions were further fractionated according to hydrophobicity on octyl-Sepharose in Triton X-100 gradients. The glycosaminoglycan chains, intact or degraded by chemical or enzymic methods were then analysed by gel chromatography on Sepharose CL-6B, Bio-Gel P-6, ion exchange HPLC and gel electrophoresis. 2. Three types of dermatan-sulphate chains were identified on the basis of disaccharide composition and chain length. They were derived from the large proteoglycan, two small proteoglycans and a cell-associated proteoglycan with core proteins of 90 kDa and 45 kDa. Intracellular, free dermatan-sulphate chains were very similar to those of the small proteoglycans. 3. Heparan-sulphate chains from different proteoglycans had, in spite of small but distinct differences in size, strikingly similar compositional features. They contained similar amounts of D-glucuronate, L-iduronate (with or without sulphate) and N-sulphate groups. They all displayed heparin-lyase-resistant domains with average molecular mass of 10-15 kDa. The heparan-sulphate chains from proteoglycans with 250-kDa and 350-kDa cores were the largest greater than 50 kDa), containing an average of four or five domains, in contrast to heparan-sulphate chains from the small heparan-sulphate proteoglycans which had average molecular mass of 45 kDa and consisted of three or four such domains. Free, cell-associated heparan-sulphate chains were heterogeneous in size (5-45 kDa). 4. These results suggest that the core protein may have important regulatory functions with regard to dermatan-sulphate synthesis. On the other hand, synthesis of heparan sulphate may be largely controlled by the cell that expresses a particular proteoglycan core protein.

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