| 1. |
- Breimer, Michael, 1951, et al.
(författare)
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Blood group type glycosphingolipids from the small intestine of different animals analysed by mass spectrometry and thin-layer chromatography. A note on species diversity.
- 1981
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Ingår i: Journal of biochemistry. - 0021-924X. ; 90:3, s. 589-609
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Tidskriftsartikel (refereegranskat)abstract
- The total non-acid glycosphingolipids were isolated from the small intestine of cat, cod-fish, guinea-pig, hen, mouse, rabbit, and two strains of rat. The samples were analyzed by thin-layer chromatography and mass spectrometry and for immunological activity. Mass spectrometry of permethylated and LiAlH4-reduced permethylated derivatives allowed the interpretation of the structures (carbohydrate sequence and ceramide composition) of up to 9 glycolipid species in one mixture. The interpretation was facilitated by a temperature programming of the direct inlet probe, leading to a successive evaporation of glycolipid species mainly according to the number of sugars. The structures concluded could in most cases be assigned to the separate bands revealed by thin-layer chromatography. Antigenic determinants proposed by the spectra were settled by immunological analysis. Thus, Forssman glycolipid was identified in cat, guinea-pig, hen and mouse, blood group A glycolipids in cat, rabbit, and rat and blood group B glycolipids in rabbit and rat. No Lewis activity was found. Certain ceramide types were demonstrated to exist preferentially in some glycolipids. Globoside and Forssman glycolipids (globo series) had a less hydroxylated ceramide (one free hydroxyl) compared to most fucolipids and other glycolipids (two or three hydroxyls). In conclusion, glycolipid patterns of intestine vary between species, and individuals of the same species.
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| 2. |
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| 3. |
- Breimer, Michael, 1951, et al.
(författare)
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The specific glycosphingolipid composition of human ureteral epithelial cells.
- 1985
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Ingår i: Journal of biochemistry. - 0021-924X. ; 98:5, s. 1169-80
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Tidskriftsartikel (refereegranskat)abstract
- Total non-acid and acid glycolipid fractions were isolated from epithelial cell scrapings and the non-epithelial residue of a human upper ureter. The glycolipid fractions were structurally characterized as total mixtures by thin-layer chromatography, mass spectrometry, and proton NMR spectroscopy. Selected structural information was also obtained on binding of monoclonal antibodies and bacteria to the thin-layer chromatograms. The major epithelial cell glycolipids were Glc beta 1-1ceramide (75%), dihexosylceramide (10%) and NeuAcLacceramide (10%). In addition, 8 minor glycolipids belonging to the blood group P, Lewis and ABO systems were identified. The major glycolipids of the non-epithelial residues were mono- and dihexosylceramides together with globotriaosyl- and globotetraosylceramides. The epithelial mono- and diglycosylceramide compounds had an unusual ceramide composition with mainly C18 and C20 trihydroxy long chain bases in combination with C22-C24 hydroxy fatty acids in contrast to the non-epithelial glycolipids which contained mainly C18 dihydroxy long chain bases in combination with C16-C24 non-hydroxy fatty acids.
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| 4. |
- Ciopraga, J, et al.
(författare)
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Isolectins from Solanum tuberosum with different detailed carbohydrate binding specificities: unexpected recognition of lactosylceramide by N-acetyllactosamine-binding lectins.
- 2000
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Ingår i: Journal of biochemistry. - 0021-924X. ; 128:5, s. 855-67
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Tidskriftsartikel (refereegranskat)abstract
- Glycosphingolipid recognition by two isolectins from Solanum tuberosum was compared by the chromatogram binding assay. One lectin (PL-I) was isolated from potato tubers by affinity chromatography, and identified by MALDI-TOF mass spectrometry as a homodimer with a subunit molecular mass of 63,000. The other (PL-II) was a commercial lectin, characterized as two homodimeric isolectins with subunit molecular masses of 52,000 and 55,000, respectively. Both lectins recognized N-acetyllactosamine-containing glycosphingolipids, but the fine details of their carbohydrate binding specificities differed. PL-II preferentially bound to glycosphingolipids with N-acetyllactosamine branches, as Galbeta4GlcNAcbeta6(Galbeta4GlcNAcbeta3)Galbeta4Glcbeta1C er. PL-I also recognized this glycosphingolipid, but bound equally well to the linear glycosphingolipid Galbeta4GlcNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer. Neolactotetraosylceramide and the B5 pentaglycosylceramide were also bound by PL-I, while other glycosphingolipids with only one N-acetyllactosamine unit were non-binding. Surprisingly, both lectins also bound to lactosylceramide, with an absolute requirement for sphingosine and non-hydroxy fatty acids. The inhibition of binding to both lactosylceramide and N-acetyllactosamine-containing glycosphingolipids by N-acetylchitotetraose suggests that lactosylceramide is also accomodated within the N-acetylchitotetraose/N-acetyllactosamine-binding sites of the lectins. Through docking of glycosphingolipids onto a three-dimensional model of the PL-I hevein binding domain, a Galbeta4GlcNAcbeta3Galbeta4 binding epitope was defined. Furthermore, direct involvement of the ceramide in the binding of lactosylceramide was suggested.
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| 5. |
- Ekman, Pia, et al.
(författare)
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The quantity of protein-bound (32P)phosphotyrosine in hepatocytes and fibroblasts : The effects of tyrosine protein kinase activating agents
- 1987
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Ingår i: Journal of Biochemistry (Tokyo). - 0021-924X .- 1756-2651. ; 101:4, s. 863-870
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Tidskriftsartikel (refereegranskat)abstract
- Tyrosine protein kinase activities have been demonstrated in transformed and normal cell systems. So far, few data on the quantity of protein-bound phosphotyrosine in intact cells have been published. A knowledge of the stoichiometric increase in phosphotyrosine in cells after hormonal induction could be of interest when evaluating the importance of the tyrosine protein kinase activities found. By the addition of a known amount of unlabeled phosphotyrosine to the precipitated protein of 32P-phosphate-labeled cells it was possible after alkaline hydrolysis to spectrophotometrically follow the phosphotyrosine during consecutive chromatographies of the material. From the specific radioactivity of the purified phosphotyrosine the initial concentration of [32P]phosphotyrosine could be calculated. The method proved to be useful for the determination of [32P]phosphotyrosine is small amounts of cells. The minimum detectable amount of [32P]phosphotyrosine was about 1 pmol, and as an example, only 2.5 X 10(6) fibroblasts were needed. By this method it was shown that platelet-derived growth factor increased protein-bound [32P]phosphotyrosine from 600 to 3,200 pmol/g of fibroblasts, while insulin only increased the [32P]phosphotyrosine from 110 to 120 pmol/g of hepatocytes.
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| 6. |
- Eller, Marika, et al.
(författare)
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Substrate specificity of protein kinase C studied with peptides containing D-amino acid residues.
- 1993
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Ingår i: Journal of Biochemistry. - 0021-924X. ; 114:2, s. 177-180
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Tidskriftsartikel (refereegranskat)abstract
- A set of stereoisomeric nonapeptides KRPSQRAKY with one, two, or all L-amino acid residues replaced by the corresponding D-amino acids, and two analogs with L- and D-threonine instead of serine, were synthesized and tested as substrates for protein kinase C. All of the peptides were phosphorylated by the enzyme. The maximal rate of the reaction with the all-D peptide was more than one order of magnitude lower than that for all-L peptide with serine. The same applied to the peptides with D-Ser or with D-Arg in position +2 with respect to Ser. The Km values for the peptides containing one D-amino acid were close to that for the prototype peptide (53 microM). On the other hand, when two or more D-amino acids were present, the Km value increased considerably. Replacement of serine by threonine also reduced the phosphorylation rate and increased the Km values. One can conclude that the stereospecificity of protein kinase C is much less pronounced than that of protein kinase A, which is in agreement with the less clearly pronounced substrate specificity of the former enzyme.
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| 7. |
- Ellouze, C., et al.
(författare)
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Dissociation of non-complementary second DNA strand from RecA filament without ATP hydrolysis: mechanism of the search for homologous DNA
- 1997
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Ingår i: Journal of Biochemistry. - 0021-924X. ; 121:6, s. 1070-1075
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Tidskriftsartikel (refereegranskat)abstract
- RecA protein catalyzes the DNA annealing and mimics the DNA strand exchange reaction in vitro in the presence of ATP or its non-hydrolyzable analog, adenosine 5'-O-3-thiotriphosphate (ATP gamma S). For these activities RecA coordinates two DNA molecules [Takahashi, M. and Norden, B. (1994) Adv. Biophys, 30, 1-35]. In order to get a better understanding of how RecA performs the search for sequence complementarity or homology between two DNA molecules, the association and dissociation kinetics oa second DNA molecule to and from RecA in the presence of ATP gamma S have been investigated, The kinetics were monitored by fluorescence measurements of partly etheno-modified poly(dA) assisted by linear dichroism measurements of the flow-oriented complex. The association of the second DNA is fast;, regardless of whether the sequence is complementary or not. Bg contrast, the dissociation kinetics is strongly dependent on sequence complementarity, If the second DNA is complementary to the first, dissociation is extremely slow, whilst that of non-complementary second DNA is fast, In no case does the first DNA leave the RecA fiber, Our findings indicate that the dissociation step is important in the search for homology by RecA.
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| 8. |
- Fei, Xiaowen, et al.
(författare)
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An Fe deficiency responsive element with a core sequence of TGGCA regulates the expression of FEA1 in Chlamydomonas reinharditii
- 2009
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Ingår i: Journal of biochemistry. - Oxford, UK : Oxford University Press. - 1756-2651 .- 0021-924X. ; 146:2, s. 157-166
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Tidskriftsartikel (refereegranskat)abstract
- Iron is essential to the unicellular green alga Chlamydomonas, but the molecular mechanism for response to iron deficiency remains largely unknown. In previous studies, we have identified FOX1 and ATX1 FEREs (Fe deficiency-responsive elements) as important regulation components of iron response in this organism. Here we present another iron regulated gene FEA1, which promoter was analysed by using a 5'-and 3'-end deletion and a scanning mutagenesis assay. The results reveal that the co-existence of -273/-188 and -118/-49 regions from transcriptional start site of FEA1 were sufficient and necessary for Fe deficiency-induced expression. Further deletion analysis indicates both -273/-253 and -103/-85 regions are essential for inducible expression. The scanning mutagenesis analysis of these regions identifies two cis-acting elements: the FeaFeRE1 at -273/-259 (CTGCGGTGGCAAAGT) and FeaFeRE2 at -106/-85 (CCGCCGCNNNTGGCACCAGCCT). Sequence comparison of FeaFeRE1 and FeaFeRE2 reveals a core sequence of TGGCA, which had been found in our previously reported Fe-deficiency-inducible gene ATX1. Moreover, we show that the promoter region of several genes, including FRE1, IRT1, ISCA, ZRT1, ZRT5, NRAMP2 and COPT1, also contains this core sequence, suggesting that at least two classes FeRE elements exist in Clamydomonas, one in FEA1 and ATX1 and others the second in FOX1, FEA2, MTP4, NRAMP3 and RBOL1.
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| 9. |
- Heldin, Paraskevi, et al.
(författare)
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Deregulation of hyaluronan synthesis, degradation and binding promotes breast cancer
- 2013
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Ingår i: Journal of Biochemistry (Tokyo). - : Oxford University Press (OUP). - 0021-924X .- 1756-2651. ; 154:5, s. 395-408
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Tidskriftsartikel (refereegranskat)abstract
- Clinical and experimental data indicate that hyaluronan accumulates in breast cancer compared with normal breast epithelium, which correlates to poor prognosis. In this review, we discuss the expression of genes encoding enzymes that synthesize or degrade hyaluronan, i.e. hyaluronan synthases and hyaluronidases or bind hyaluronan, i.e. CD44 and receptor for hyaluronan-mediated motility (RHAMM, also designated as HMMR or CD168), in relation to breast cancer progression. Hyaluronan and hyaluronan receptors have multi-faceted roles in signalling events in breast cancer. A better understanding of the molecular mechanisms underlying these signalling pathways is highly warranted and may lead to improvement of cancer treatment.
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| 10. |
- Holgersson, Jan, et al.
(författare)
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Glycosphingolipids of human large intestine: detailed structural characterization with special reference to blood group compounds and bacterial receptor structures.
- 1991
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Ingår i: Journal of biochemistry. - 0021-924X. ; 110:1, s. 120-31
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Tidskriftsartikel (refereegranskat)abstract
- Non-acid glycosphingolipid expression was studied in the large intestines from four individuals with the A1Le(a-b+), BLe(a-b+), and OLe(a-b+) blood group phenotypes. In the A1Le(a-b+) case, specimens were taken from the ascending and sigmoid parts of the large intestine in order to compare the expression of glycolipids in the proximal and distal regions of the intestine. In one blood group OLe(a-b+) individual, epithelial cells were isolated from the residual stroma to compare the glycolipid compositions in these two tissue compartments. GlcCer, GalCer, LacCer, Gb3Cer, and Gb4Cer were the major compounds in all three individuals, as shown by mass spectrometry, proton NMR spectroscopy, and degradation studies. The Lea-5 glycolipid was the major complex blood group glycolipid in all individuals, except in the proximal ascending part of the large intestine of the A1Le(a-b+) case, in which the Leb-6 glycolipid was predominant. There were trace amounts of blood group ABH glycolipids, in agreement with the ABO blood group phenotypes of the donors, Lewis antigens with more than six sugar residues in the carbohydrate chain, and blood group X and Y glycolipid antigens. The epithelial cells were dominated by monoglycosylceramides and the Lea-5 glycolipid, while only trace amounts of di-, tri-, and tetraglycosylceramide structures were present. No reactivity was seen in the epithelial cell fraction with Gal alpha 1-4Gal specific Escherichia coli, anti-Pk, or anti-P antibodies, indicating the absence of the glycolipid-borne Gal alpha 1-4Gal sequence in human large intestinal epithelial cells.
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