| 1. |
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| 2. |
- Kuil, Teun, et al.
(författare)
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Pyrophosphate as allosteric regulator of ATP-phosphofructokinase in Clostridium thermocellum and other bacteria with ATP- and PPi-phosphofructokinases
- 2023
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861 .- 1096-0384. ; 743
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Tidskriftsartikel (refereegranskat)abstract
- The phosphofructokinase (Pfk) reaction represents one of the key regulatory points in glycolysis. While most organisms encode for Pfks that use ATP as phosphoryl donor, some organisms also encode for PPi-dependent Pfks. Despite this central role, the biochemical characteristics as well as the physiological role of both Pfks is often not known. Clostridium thermocellum is an example of a microorganism that encodes for both Pfks, however, only PPi-Pfk activity has been detected in cell-free extracts and little is known about the regulation and function of both enzymes. In this study, the ATP- and PPi-Pfk of C. thermocellum were purified and biochemically characterized. No allosteric regulators were found for PPi-Pfk amongst common effectors. With fructose-6-P, PPi, fructose-1,6-bisP, and Pi PPi-Pfk showed high specificity (KM < 0.62 mM) and maximum activity (Vmax > 156 U mg-1). In contrast, ATP-Pfk showed much lower affinity (K0.5 of 9.26 mM) and maximum activity (14.5 U mg-1) with fructose-6-P. In addition to ATP, also GTP, UTP and ITP could be used as phosphoryl donors. The catalytic efficiency with GTP was 7-fold higher than with ATP, suggesting that GTP is the preferred substrate. The enzyme was activated by NH4+, and pronounced inhibition was observed with GDP, FBP, PEP, and especially with PPi (Ki of 0.007 mM). Characterization of purified ATP-Pfks originating from eleven different bacteria, encoding for only ATP-Pfk or for both ATP- and PPi-Pfk, identified that PPi inhibition of ATP-Pfks could be a common phenomenon for organisms with a PPi-dependent glycolysis.
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| 3. |
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| 4. |
- Norlin, Maria, et al.
(författare)
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Enzymatic activation in vitamin D signaling : Past, present and future
- 2023
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier. - 0003-9861 .- 1096-0384. ; 742
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Forskningsöversikt (refereegranskat)abstract
- Vitamin D signaling is important in regulating calcium homeostasis essential for bone health but also displays other functions in cells of several tissues. Disturbed vitamin D signaling is linked to a large number of diseases. The multiple cytochrome P450 (CYP) enzymes catalyzing the different hydroxylations in bioactivation of vitamin D3 are crucial for vitamin D signaling and function. This review is focused on the progress achieved in identification of the bioactivating enzymes and their genes in production of 1α,25-dihydroxyvitamin D3 and other active metabolites. Results obtained on species- and tissue-specific expression, catalytic reactions, substrate specificity, enzyme kinetics, and consequences of gene mutations are evaluated. Matters of incomplete understanding regarding the physiological roles of some vitamin D hydroxylases are critically discussed and the authors will give their view of the importance of each enzyme for vitamin D signaling. Roles of different vitamin D receptors and an alternative bioactivation pathway, leading to 20-hydroxylated vitamin D3 metabolites, are also discussed. Considerable progress has been achieved in knowledge of the vitamin D3 bioactivating enzymes. Nevertheless, several intriguing areas deserve further attention to understand the pleiotropic and diverse activities elicited by vitamin D signaling and the mechanisms of enzymatic activation necessary for vitamin D-induced responses.
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| 5. |
- Oliw, Ernst H., 1948-
(författare)
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Iron and manganese lipoxygenases of plant pathogenic fungi and their role in biosynthesis of jasmonates
- 2022
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier. - 0003-9861 .- 1096-0384. ; 722
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Forskningsöversikt (refereegranskat)abstract
- Lipoxygenases (LOX) contain catalytic iron (FeLOX), but fungi also produce LOX with catalytic manganese (MnLOX). In this review, the 3D structures and properties of fungal LOX are compared and contrasted along with their associations with pathogenicity. The 3D structures and properties of two MnLOX (Magnaporthe oryzae, Geaumannomyces graminis) and the catalysis of four additional MnLOX have provided information on the metal centre, substrate binding, oxygenation, tentative O-2 channels, and biosynthesis of exclusive hydroperoxides. In addition, the genomes of other plant pathogens also code for putative MnLOX. Crystals of the 13S-FeLOX of Fusarium graminearum revealed an unusual altered geometry of the Fe ligands between mono- and dimeric structures, influenced by a wrapping sequence extension near the C-terminal of the dimers. In plants, the enzymes involved in jasmonate synthesis are well documented whereas the fungal pathway is yet to be fully elucidated. Conversion of deuterium-labelled 18:3n-3, 18:2n-6, and their 13S-hydroperoxides to jasmonates established 13S-FeLOX of F. oxysporum in the biosynthesis, while subsequent enzymes lacked sequence homologues in plants. The Rice-blast (M. oryzae) and the Take-all (G. graminis) fungi secrete MnLOX to support infection, invasive hyphal growth, and cell membrane oxidation, contributing to their devastating impact on world production of rice and wheat.
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| 6. |
- Oliw, Ernst H., 1948-
(författare)
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Linoleate diol synthase related enzymes of the human pathogens Histoplasma capsulatum and Blastomyces dermatitidis
- 2020
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861 .- 1096-0384. ; 696
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Tidskriftsartikel (refereegranskat)abstract
- Histoplasma capsulatum is an ascomyceteous fungus and a human lung pathogen, which is present in river valleys of the Americas and other continents. H. capsulatum and two related human pathogens, Blasmomyces dermatitidis and Paracoccidioides brasiliensis, belongs to the Ajellomycetaceae family. The genomes of all three species code for three homologous and tentative enzymes of the linoleate diol synthase (LDS) family of fusion enzymes with dioxygenase (DOX) and cytochrome P450 domains. One group aligned closely with 8R-DOX-5,8-LDS of Aspergilli, which oxidizes linoleic acid to 5S,8R-dihydroxylinoleic acid; this group was not further investigated. The second group aligned with 10R-DOX-epoxy alcohol synthase (EAS) of plant pathogens. Expression of this enzyme from B. dermatitidis revealed only 10R-DOX activities, i.e., oxidation of linoleic acid to 10R-hydroperoxy-8E,12Z-octadecadienoic acid. The third group aligned in a separate entity. Expression of these enzymes of H. capsulatum and B. dermatitidis revealed no DOX activities, but both enzymes transformed 13S-hydroperoxy-9Z,11E-octadecadienoic acid efficiently to 12(13S)epoxy-11-hydroperoxy-9Z-octadecenoic acid. Other 13-hydroperoxides of linoleic and α-linolenic acids were transformed with less efficiency and the 9-hydroperoxides of linoleic acid were not transformed. In conclusion, a novel EAS has been found in H. capsulatum and B. dermititidis with 13S-hydroperoxy-9Z,11E-octadecadienoic acid as the likely physiological substrate.
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| 7. |
- Oliw, Ernst H., 1948-
(författare)
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Thirty years with three-dimensional structures of lipoxygenases
- 2024
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier. - 0003-9861 .- 1096-0384. ; 752
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Forskningsöversikt (refereegranskat)abstract
- The X-ray crystal structures of soybean lipoxygenase (LOX) and rabbit 15-LOX were reported in the 1990s. Subsequent 3D structures demonstrated a conserved U-like shape of the substrate cavities as reviewed here. The 8-LOX:arachidonic acid (AA) complex showed AA bound to the substrate cavity carboxylate-out with C10 at 3.4 Å from the iron metal center. A recent cryo-electron microscopy (EM) analysis of the 12-LOX:AA complex illustrated AA in the same position as in the 8-LOX:AA complex. The 15- and 12-LOX complexes with isoenzyme-specific inhibitors/substrate mimics confirmed the U-fold. 5-LOX oxidizes AA to leukotriene A4, the first step in biosynthesis of mediators of asthma. The X-ray structure showed that the entrance to the substrate cavity was closed to AA by Phe and Tyr residues of a partly unfolded α2-helix. Recent X-ray analysis revealed that soaking with inhibitors shifted the short α2-helix to a long and continuous, which opened the substrate cavity. The α2-helix also adopted two conformations in 15-LOX. 12-LOX dimers consisted of one closed and one open subunit with an elongated α2-helix. 13C-ENDOR-MD computations of the 9-MnLOX:linoleate complex showed carboxylate-out position with C11 placed 3.4 ± 0.1 Å from the catalytic water. 3D structures have provided a solid ground for future research.
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| 8. |
- Raczyński, Przemysław, et al.
(författare)
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Influence of silicon nanocone on cell membrane self-sealing capabilities for targeted drug delivery—Computer simulation study
- 2023
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861 .- 1096-0384. ; 749
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Tidskriftsartikel (refereegranskat)abstract
- Efficient and non-invasive techniques of cargo delivery to biological cells are the focus of biomedical research because of their great potential importance for targeted drug therapy. Therefore, much effort is being made to study the characteristics of using nano-based biocompatible materials as systems that can facilitate this task while ensuring appropriate self-sealing of the cell membrane. Here, we study the effects of indentation and withdrawal of nanocone on phospholipid membrane by applying steered molecular dynamics (SMD) technique. Our results show that the withdrawal process directly depends on the initial position of the nanocone. The average force and work are considerably more significant in case of the withdrawal starting from a larger depth. This result is attributed to stronger hydrophobic interactions between the nanocone and lipid tails of the membrane molecules. Furthermore, when the indenter was started from the lower initial depth, the number of lipids removed from the membrane was several times smaller than the deeper indentation. The choice of the least invasive method for nanostructure-assisted drug delivery is crucial for possible applications in medicine. Therefore, the results presented in this work might be helpful in efficient and safe drug delivery with nanomaterials.
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| 9. |
- Hansen, Dennis K., et al.
(författare)
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Engineering Bifidobacterium longum Endo-α-N-acetylgalactosaminidase for Neu5Acα2-3Galβ1-3GalNAc reactivity on Fetuin
- 2022
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861. ; 725
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Tidskriftsartikel (refereegranskat)abstract
- Endo-α-N-acetylgalactosaminidase from Bifidobacterium longum (EngBF) belongs to the glycoside hydrolase family GH101 and has a strict preference towards the mucin type glycan, Galβ1-3GalNAc, which is O-linked to serine or threonine residues on glycopeptides and -proteins. While other enzymes of the GH101 family exhibit a wider substrate spectrum, no GH101 member has until recently been reported to process the α2-3 sialidated mucin glycan, Neu5Acα2-3Galβ1-3GalNAc. However, work published by others (ACS Chem Biol 2021, 16, 2004–2015) during the preparation of the present manuscript demonstrated that the enzymes from several bacteria are able to hydrolyze this glycan from the fluorophore, methylumbelliferyl. Based on molecular docking using the EngBF homolog, EngSP from Streptococcus pneumoniae, substitution of active site amino acid residues with the potential to allow for accommodation of Neu5Acα2-3Galβ1-3GalNAc were identified. Based on this analysis, the mutant EngBF variants W750A, Q894A, K1199A, E1294A and D1295A were prepared and tested, for activity towards the Neu5Acα2-3Galβ1-3GalNAc O-linked glycan present on bovine fetuin. Among the mutant EngBF variants listed above, only E1294A was shown to release Neu5Acα2-3Galβ1-3GalNAc from fetuin, which subsequently was also demonstrated for the substitutions: E1294 M, E1294H and E1294K. In addition, the kcat/KM of the EngBF variants for cleavage of the Neu5Acα2-3Galβ1-3GalNAc glycan increased between 5 and 70 times from pH 4.5 to pH 6.0.
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| 10. |
- Tutzauer, Julia, et al.
(författare)
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G protein-coupled estrogen receptor (GPER)/GPR30 forms a complex with the β1-adrenergic receptor, a membrane-associated guanylate kinase (MAGUK) scaffold protein, and protein kinase A anchoring protein (AKAP) 5 in MCF7 breast cancer cells
- 2024
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Ingår i: Archives of Biochemistry and Biophysics. - 0003-9861. ; 752
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Tidskriftsartikel (refereegranskat)abstract
- G protein-coupled receptor 30 (GPR30), also named G protein-coupled estrogen receptor (GPER), and the β1-adrenergic receptor (β1AR) are G protein-coupled receptors (GPCR) that are implicated in breast cancer progression. Both receptors contain PSD-95/Discs-large/ZO-1 homology (PDZ) motifs in their C-terminal tails through which they interact in the plasma membrane with membrane-associated guanylate kinase (MAGUK) scaffold proteins, and in turn protein kinase A anchoring protein (AKAP) 5. GPR30 constitutively and PDZ-dependently inhibits β1AR-mediated cAMP production. We hypothesized that this inhibition is a consequence of a plasma membrane complex of these receptors. Using co-immunoprecipitation, confocal immunofluorescence microscopy, and bioluminescence resonance energy transfer (BRET), we show that GPR30 and β1AR reside in close proximity in a plasma membrane complex when transiently expressed in HEK293. Deleting the GPR30 C-terminal PDZ motif (-SSAV) does not interfere with the receptor complex, indicating that the complex is not PDZ-dependent. MCF7 breast cancer cells express GPR30, β1AR, MAGUKs, and AKAP5 in the plasma membrane, and co-immunoprecipitation revealed that these proteins exist in close proximity also under native conditions. Furthermore, expression of GPR30 in MCF7 cells constitutively and PDZ-dependently inhibits β1AR-mediated cAMP production. AKAP5 also inhibits β1AR-mediated cAMP production, which is not additive with GPR30-promoted inhibition. These results argue that GPR30 and β1AR form a PDZ-independent complex in MCF7 cells through which GPR30 constitutively and PDZ-dependently inhibits β1AR signaling via receptor interaction with MAGUKs and AKAP5.
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| 11. |
- Guo, Zhiming, et al.
(författare)
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Sensitive determination of Patulin by aptamer functionalized magnetic surface enhanced Raman spectroscopy (SERS) sensor
- 2023
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Ingår i: Journal of Food Composition and Analysis. - : Elsevier BV. - 0889-1575 .- 1096-0481. ; 115
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Tidskriftsartikel (refereegranskat)abstract
- Food pollution caused by Patulin (PAT) seriously threatens the safety of human diets and has attracted extensive attention. Early and accurate detections of PAT are essential to prevent further toxin spreading and contamination. A surface enhanced Raman scattering (SERS) aptasensor was fabricated by combining a gold-silver core shell structure containing signal molecule (ADANRs) and chitosan modified magnetic nanoparticles (CS-Fe3O4). The modified ADANRs with the complementary chain of the aptamer (SH-cDNA-ADANRs) which were served as the signal probes and the aptamer modified CS-Fe3O4 (NH2-apt-CS-Fe3O4) were served as the capture probes. In addition to the ability to recognize the target PAT, the capture probe also showed a strong enrichment ability under the action of external magnetic force. The intraparticle plasma coupling between the inner gold core and the outer silver shell can greatly improve the SERS activity of the signal molecules. SERS aptasensor was used to collect the spectra of actual apple samples spiked with different PAT content. The minimum detection limit of SERS aptasensor for detecting PAT in actual samples was 0.0384 ng/mL and the recovery rate range was from 96.3% to 108%. In conclusion, the sensitive and specific SERS aptasensor detection of PAT based on aptamer functionalized nanoparticles exhibited great potential for practical application in mycotoxin detection and analysis.
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