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81.
Kazuo Iwai Masahiro Kohashi Tsutomu Itadani Tetsuya Suzuki 《Bioscience, biotechnology, and biochemistry》2013,77(5):1141-1147
Guanosine triphosphate cyclohydrolase (EC 3.5.4.16) was previously shown to exist in two forms (GTP cyclohydrolase D-I and D-II) in Serratia indica IFO 3759, and they were homogeneously isolated. The present study deals with the characterization of their reaction products. A fluorescent product formed from guanosine triphosphate by GTP cyclohydrolase D-II was identified as 7,8-dihydroneopterin triphosphate by its absorption spectra, phosphate analysis and gas chromatography-mass spectrometry of the dephosphorylated trimethylsilyl derivative. After oxidation and dephosphorylation, the d-erythro configuration of the side chain was made clear by the elution profile on ECTEOLA-cellulose chromatography, Rf values on thin-layer chromatography and by biological activity to Crithidia fasciculata ATCC 12857. The fluorescent products from GTP cyclohydrolase D-I and D-II were indistinguishable. 相似文献
82.
Shigehiro Kamoda Naoto Habu Masahiro Samejima Tomotaka Yoshimoto 《Bioscience, biotechnology, and biochemistry》2013,77(10):2757-2761
A novel dioxygenase, lignostilbene-a,β-dioxygenase (LSD), which catalyzes cleavage of the interphenyl double bond of lignin-derived stilbenes, was isolated. Four isozymes of LSD were separated from cell-free extracts of Pseudomonas sp. TMY1009 by ion-exchange chromatography on a DEAE- Toyopearl column. The major isozyme, LSD-I, was purified to electrophoretic homogeneity and characterized.LSD-I cleaved the interphenyl double bond of l,2-bis(4′-hydroxy-3′-methoxyphenyl)ethylene with the optimum pH at 8.5. The Km of LSD-I was 11 μm for the stilbene and 110/iM for oxygen. The molecular weight of LSD-I, which is composed of two identical subunits, was estimated to be 94,000. LSD-I contained 1 g atom of iron per 1 mol of enzyme protein. 相似文献
83.
Seizo Sumida Masahiro Takaki Junshi Miyamoto 《Bioscience, biotechnology, and biochemistry》2013,77(10):1576-1579
A rapid and sensitive method is presented for the determination of micro-quantities (1 to 100 μg) of N-methyl carbamates as dinitrophenyl methylamine (DNP-MA) by electron capture gas liquid chromatography (GLC). The method described is characterized by rapidity and simplicity of procedure due to an improvement made in the present investigation, i.e., hydrolysis of an N-methyl carbamate and dinitrophenylation of the resulting methylamine with 2, 4-dinitro-1-fluorobenzene (DNFB) were accomplished simultaneously in a single reaction mixture. A novel approach was also made to eliminate unreacted DNFB by conversion to dinitrophenyl glycine (DNP-glycine). 相似文献
84.
Masahiro Hori Kazuo Kakiki Saburo Suzuki Tomomasa Misato 《Bioscience, biotechnology, and biochemistry》2013,77(8):1280-1291
(1) Chitin-UDP acetylglucosaminyltransferase (E.C. 2.4.1.16., chitin synthetase) in the cell-free system from phytopathogenic fungus Piricularia oryzae, and effects of various polyoxins and related compounds on the enzyme activity were studied. Polyoxins A~M, polyoxin A derivatives, polyoxin C derivatives, 5′-amino-5′-deoxyuridine, uridine and thymidine inhibited equally the incorporation of N-acetylglucosamine (GlcNAc) from UDP-N-acetylglucosamine (UDP-GlcNAc) into chitin. (2) Competition between the above inhibitors and UDP-GlcNAc was observed by kinetic studies. The Km for UDP-GlcNAc was determined to be 3.3 × 10?3 m and the Ki values for polyoxins A~M, except polyoxin C, were found to be in the range of 3.3 × 10?5 m to 3.4 × 10?6 m. For polyoxin C, 5′-amino-5′-deoxyuridine and uridine, the Ki values of 2.7 × 10?3 m, 8.0 × 10?3 m and 3.0 × 10?3 m were given, respectively. The inhibitor constants for other related compounds were also calculated. (3) The values of binding affinity, ?ΔG, for formation of substrate- or inhibitor-enzyme complexes were calculated from the Km or Ki values. In addition, partial binding affinities, ?Δg, for certain moieties or groups of polyoxins were estimated from the ?ΔG. For instance, the ?ΔG values for UDP-GlcNAc and polyoxin L were 5.7 kcal/mole and 9.2 kcal/mole, respectively. And the ?Δg values for the nucleoside moiety (part I), the carbamylpolyoxamic acid moiety (part II) and the carboxyl group at C5′ position of polyoxin L were 5.2, 3.5 and 0.7 kcal/mole, respectively. (4) From the results obtained, the mechanism of action and relation between chemical structure and competitive inhibition of chitin synthetase were discussed. 相似文献
85.
Kyoko Saio Masahiro Kajikawa Tokuji Watanabe 《Bioscience, biotechnology, and biochemistry》2013,77(6):890-898
Relation between sulfhydryl groups in soybean proteins and the physical properties of tofu was studied. Changes in the amount of sulfhydryl groups by heating or treatment with urea were more rapid in 11S protein as compared with 7S protein. Moreover, by changing the amount of sulfhydryl groups in proteins by N-ethylmaleimide, 2-mercapto-ethanol and dithiothreitol, the physical properties of tofu from 11S protein were more significantly effected than that from 7S protein. Namely, tofu-gel from 11S. protein got harder and stronger as the amount of sulfhydryl groups increased.The results may suggest that tofu prepared from IIS protein has more disulfide bonds in its gel than that from 7S protein. 相似文献
86.
Vu Huu Thanh Kazuyoshi Okubo Kazuo Shibasaki 《Bioscience, biotechnology, and biochemistry》2013,77(7):1501-1503
Two kinds of N-acetylmuramidase, M-1 and M-2 enzymes, that were isolated from the cultural broth of Stm. globisporus 1829, were remarkably different in amino acid composition, immunological properties and modes of lytic action from each other. The M-1 enzyme was composed of 186 amino acid residues of which two moles were of half cystine, while the M-2 enzyme was composed of 99 amino acid residues with no cysteine. The hydrolyzing action of the M-2 enzyme was suppressed by the presence of an O-acetyl group on muramic acid residues in the peptidoglycan moiety, while that of the M-l enzyme was independent of the presence of O-acetyl groups. However, the hydrolyzing activity of both enzymes was enhanced when some muramic acid residues were substituted with stem peptides containing alanine, isoglutamine and lysine. 相似文献
87.
Koichi Ogata Tatsurokuro Tochikura Masahiro Osugi Shojiro Iwahara 《Bioscience, biotechnology, and biochemistry》2013,77(2):176-180
The production of pimelic acid from azelaic acid by microorganisms was studied. About 100 strains of bacteria which were able to utilize azelaic acid as a sole carbon source were isolated from soil and other natural materials. Among these bacteria, several strains produced a large quantity of an organic acid (pimelic acid) from azelaic acid in their culture fluids during the cultivation. The acid was isolated from the culture fluid of strain A133 in crystalline form. The crystal was identified as pimelic acid by physicochemical and biological methods.From the results of investigations on the morphological and physiological characters, the bacterial strain A133 was assumed to be Micrococcus sp. 相似文献
88.
Keisuke Kitamura Kazuyoshi Okubo Kazuo Shibasaki 《Bioscience, biotechnology, and biochemistry》2013,77(5):1083-1085
Kinetics of the acyl transfer catalyzed by Xanthomonas α-amino acid ester hydrolase was studied. The enzyme hydrolyzed d-α-phenylglycine methyl ester (d-PG-OMe) to give equimolar amounts of d-α-phenylglycine and methanol. With d-PG-OMe as an acyl donor and 7-amino-3-deacetoxy-cephalosporanic acid (7-ADCA) as an acyl acceptor, the enzyme transferred the acyl group from d-PG-OMe to 7-ADCA in competition with water. The addition of amine nucleophiles (7-ADCA and 6-aminopenicillanic acid) decreased the molecular activity (ko) of the enzyme-catalyzed hydrolysis of d-PG-OMe, whereas it did not alter the Michaelis constant (KM), and plots of l/ko against the initial concentration of a nucleophile (no) gave a straight line. These results support the assumptions that the overall process for hydrolysis and acyl transfer proceeds through a common acyl-enzyme intermediate, that the acylation step of the enzyme is rate-limiting, and that the transfer competes with the hydrolysis of the acyl donor. 相似文献
89.
Hiroto Nishijima Kouichi Nozaki Masahiro Mizuno Tsutomu Arai 《Bioscience, biotechnology, and biochemistry》2013,77(5):738-746
The xylanase (Xyn10B) that strongly adsorbs on microcrystalline cellulose was isolated from Driselase. The Xyn10B contains a Carbohydrate-binding module family 1 (CBM1) (IrpCBMXyn10B) at N-terminus. The canonical essential aromatic residues required for cellulose binding were conserved in IrpCBMXyn10B; however, its adsorption ability was markedly higher than that typically observed for the CBM1 of an endoglucanase from Trametes hirsuta (ThCBMEG1). An analysis of the CBM-GFP fusion proteins revealed that the binding capacity to cellulose (7.8 μmol/g) and distribution coefficient (2.0 L/μmol) of IrpCBMXyn10B-GFP were twofold higher than those of ThCBMEG1-GFP (3.4 μmol/g and 1.2 L/μmol, respectively), used as a reference structure. Besides the canonical aromatic residues (W24-Y50-Y51) of typical CBM1-containing proteins, IrpCBMXyn10B had an additional aromatic residue (Y52). The mutation of Y52 to Ser (IrpCBMY52S-GFP) reduced these adsorption parameters to 4.4 μmol/g and 1.5 L/μmol, which were similar to those of ThCBMEG1-GFP. These results indicate that Y52 plays a crucial role in strong cellulose binding. 相似文献
90.
Hajime Katano Masahiro Takakuwa Takafumi Itoh 《Bioscience, biotechnology, and biochemistry》2013,77(7):1057-1060
A colorimetric method for the reducing monosaccharide determination is optimized for the assay of glucose isomerase, which converts glucose (Glc) to fructose (Fru). Test solution was mixed with 20-fold volume of the 50 mM Na2SiO3, 600 mM Na2MoO4, and 0.95 M HCl aqueous solution (pH 4.5), in which a yellow molybdosilicate species was formed. The mixture was kept at 70 °C for 30 min. Test solution containing 10 mM level Fru gave a remarkable blue reaction mixture, in which the Mo(VI) species was reduced by Fru to form a blue molybdosilicate species. The blueness increased with the Fru concentration. Glc cannot render the reaction mixture blue as strong as Fru. Thus, the colorimetric method can be used advantageously for the determination of 10 mM level Fru in the Glc isomerase reaction mixture, even in the presence of 100 mM level Glc, and has been applied successfully to the microtiter plate assay of the enzyme. 相似文献