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51.
Anthony John Pastore Alvaro Montoya Manasi Kamat Kari B. Basso James S. Italia Abhishek Chatterjee Maria Drosou Dimitrios A. Pantazis Alexander Angerhofer 《Protein science : a publication of the Protein Society》2023,32(1):e4537
Oxalate decarboxylase from Bacillus subtilis is a binuclear Mn-dependent acid stress response enzyme that converts the mono-anion of oxalic acid into formate and carbon dioxide in a redox neutral unimolecular disproportionation reaction. A π-stacked tryptophan dimer, W96 and W274, at the interface between two monomer subunits facilitates long-range electron transfer between the two Mn ions and plays an important role in the catalytic mechanism. Substitution of W96 with the unnatural amino acid 5-hydroxytryptophan leads to a persistent EPR signal which can be traced back to the neutral radical of 5-hydroxytryptophan with its hydroxyl proton removed. 5-Hydroxytryptophan acts as a hole sink preventing the formation of Mn(III) at the N-terminal active site and strongly suppresses enzymatic activity. The lower boundary of the standard reduction potential for the active site Mn(II)/Mn(III) couple can therefore be estimated as 740 mV against the normal hydrogen electrode at pH 4, the pH of maximum catalytic efficiency. Our results support the catalytic importance of long-range electron transfer in oxalate decarboxylase while at the same time highlighting the utility of unnatural amino acid incorporation and specifically the use of 5-hydroxytryptophan as an energetic sink for hole hopping to probe electron transfer in redox proteins. 相似文献
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Employing a simple one-step sucrose gradient fractionation method, gastric mucosal membrane of Syrian hamster was prepared and demonstrated to be specifically enriched in H+,K+-ATPase activity. The preparation is practically devoid of other ATP hydrolyzing activity and contains high K+-stimulated ATPase, activity of at least 4–5 fold compared to basal ATPase activity. The H+,K+-ATPase showed hydroxylamine-sensitive phosphorylation and K+-dependent dephosphorylation of the phospho-enzyme, characteristic inhibition by vanadate, omeprazole and SCH 28080, and nigericin-reversible K+-dependent H+-transport — properties characteristic of gastric proton pump One notable difference with H+,K+-ATPase of other species has been the observation of valinomycin-independent H+ transport in such membrane vesicles. It is proposed that such H+,K+-ATPase-rich hamster gastric mucosal membrane preparation might provide a unique model to study physiological aspects of H+,K+-ATPase-function in relation to HCl secretion. 相似文献
54.
Khoo Kay-Hooi; Chatterjee Delphi; Caulfield John P.; Morris Howard R.; Dell Anne 《Glycobiology》1997,7(5):653-661
The granulomatous pathology in human intestinal schistosomiasisis induced primarily by the egg antigens of schistosome, a parasitictrematode. Glycolipids and glycoproteins were extracted fromthe eggs of the two major species which infect human, Schistosomamansoni and Schistosoma japonicum, for structural characterizationbased on highly sensitive mass spectrometric analysis coupledwith chemical derivatization. Here, we demonstrate that a seriesof uniquely multifucosylated glycosphingolipids constitute themajor egg glycolipids of S.mansoni but not of S.japonicum. TheS.mansoni glycosphingolipids were found to be extended by varyingnumbers of an unusual repeating unit, 相似文献
55.
Formation of vesicular stomatitis virus nucleocapsid from cytoskeletal framework-bound N protein: possible model for structure assembly. 总被引:10,自引:0,他引:10 下载免费PDF全文
The pathway of vesicular stomatitis virus N protein from synthesis to assembly into capsids was studied by use of detergent extraction of infected HeLa cells together with protein cross-linking. One half of the newly synthesized N protein was extracted with the soluble cell proteins and, when cross-linked, never formed the N-N dimer characteristic of mature nucleocapsids. In contrast, the cytoskeleton-bound N protein first showed a diffuse spectrum of protein-protein cross-links but, after a lag of 40 min, assumed the cross-link pattern of N protein in nucleocapsids. The efficiency of forming N-N cross-linked dimers is the same for N protein on the skeleton as in nucleocapsids derived from mature virus, suggesting very similar configurations. However, the N protein bound on the skeletal framework formed several additional cross-links that were not found in mature virus and were apparently formed to cellular proteins estimated to be ca. approximately 46,000 and 60,000 in molecular weight. 相似文献
56.
High-energy alpha particles produced a dose-dependent linear increase in different lipid peroxidation products (e.g., malondialdehyde (MDA), conjugated dienes, and hydroperoxides) in the dried thin film state. An inverse dose-rate effect was observed when the dose rate was varied by changing either the alpha-particle fluence rate or the alpha-particle energy. The antioxidants alpha-tocopherol and butylated hydroxytoluene (BHT) suppressed the alpha-particle-induced lipid peroxidation in the dried thin film state, and in this respect alpha-tocopherol was found superior to BHT. It was found that alpha-tocopherol was equally efficient in inhibiting lipid peroxidations by alpha particles and ultraviolet light. 相似文献
57.
Photochemical production of psoralen - DNA monoadducts capable of subsequent photocrosslinking. 下载免费PDF全文
Irradiation of 4' -aminomethyl-4,5' ,8-trimethyl psoralen in the presence of DNA at wavelengths between 380 and 400nm leads to efficient production of monoadducts with no significant amount of crosslinking. The yield of monoadduct attainable is high (about 35 adducts per 1000 base pairs) and can be made still higher by repeated irradiation with fresh psoralen derivative. Subsequent irradiation at 350nm results in crosslinking of a almost half of the monoattached psoralen. Studies of the yield of nonoadduct and crosslink as function of irradiation wavelength show that the action spectrum for crosslink formation is blue-shifted relative to that for monoadduct formation. 相似文献
58.
S K Banerjee S N Chatterjee 《International journal of radiation biology and related studies in physics, chemistry, and medicine》1977,32(2):127-133
The ultraviolet-inactivation kinetics of a number of strains of Vibrio cholerae (classical), Vibrio cholerae (el tor), NAG vibrios and Vibrio parahaemolyticus were investigated. Statistical analyses revealed significant differences between any two of the four types of vibrio in respect to their sensitivity to U.V. 相似文献
59.
Membrane isolated from Bacillus subtilis strain 168 incorporated GlcNAc from UDP-GlcNAc directly onto undecaprenyl phosphate via transphosphorylation and subsequent transglucosylations. Chain lengths of 6, 4, and 1 units of GlcNAc were found. Approximately 80% of the isotope incorporated was extracted into chloroform:methanol (2:1 v/v), and could be distinguished from the undecaprenyl disaccharide cell wall intermediate by a different elution pattern on DEAE-cellulose (acetate form). The GlcNAc-lipid(s) were eluted from a similar column in chloroform:methanol:water (10:10:3, v/v) with 6 mM NH4COOH indicating a pyrophosphate linkage between the lipid and the GlcNAc. The GlcNAc-lipid(s) were not degraded by conditions which completely deacylated [32P]glyceryl phospholipids, but were rapidly hydrolyzed by mild acid treatment (0.005 N HCl, 90 degrees) with the release of oligosaccharide phosphate (typical of sugars linked to undecaprenyl pyrophosphate). Catalytic hydrogenation of the GlcNAc-lipid(s) resulted in the release of water-soluble sugar phosphate. Under these same conditions, undecaprenyl pyrophosphate and undecaprenyl disaccharide cell wall intermediate were similarly effected while [32P]glyceryl phospholipids remained intact. The formation of GlcNAc-lipid(s) in vitro was inhibited if membranes were prepared from cells previously treated with bacitracin. Thus, the GlcNAc-lipid(s) has the properties of undecaprenyl poly(N-acetylglucosaminyl pyrophosphate) and may represent a new synthetic role of the polyisoprenyl lipid in B. subtilis. 相似文献
60.
A K Roy B Chatterjee W F Demyan T S Nath N M Motwani 《The Journal of biological chemistry》1982,257(13):7834-7838
Hypophysectomy is known to cause complete suppression of the hepatic synthesis alpha 2u-globulin. The effect of hypophysectomy on the synthesis of alpha 2u-globulin can be reversed by multiple hormone treatment. The role of pituitary growth hormone in the multihormonal regulation of alpha 2u-globulin in rat liver was examined in the hypophysectomized male rats with and without growth hormone supplementation. Daily treatment of hypophysectomized rats with 5 alpha-dihydrotestosterone, corticosterone, thyroxine, and growth hormone for 8 days caused about 80% recovery in the hepatic content of alpha 2u-globulin and its corresponding mRNA as determined by radioimmunoassay, in vitro translation, and liquid hybridization with a cloned cDNA probe. However, omission of growth hormone from the treatment regimen failed to raise hepatic alpha 2u-globulin and its mRNA to more than 5% of the normal control. The possible effect of growth hormone on the translation of the mRNA for alpha 2u-globulin was examined with cultured hepatocytes derived from growth hormone-deficient rats. Culture of these cells in the presence of growth hormone for 24 h did not turn on the synthesis of alpha 2u-globulin. These results indicate that growth hormone regulates the synthesis of alpha 2u-globulin by acting at a step antecedent to mRNA translation. 相似文献