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Lee, Seung Goo,SUNG, MOON HEE,Esaki, Nobuyoshi,Hong, Seung Pyo,Kwak, Mi Sun 생화학분자생물학회 2001 BMB Reports Vol.32 No.5
Tyrosine phenol-lyase of thermophilic Symbiobacterium sp. SC-1, which is obligately and symbiotically dependent on thermophilic Bacillus sp. SK-1, was purified and characterized. The enzyme is composed of four identical subunits and contains approximately 1 ㏖ of pyridoxal 5'-phosphate (PLP) per ㏖ subunit as a cofactor. The enzyme showed absorption maxima at 330 and 420 nm, and lost this absorption profile by treatment with phenylhydrazine. The apparent dissociation constant, K'_D, for PLP was determined with the apoenzyme to be about 1.2 μM. The isoelectric point was 4.9. The optimal temperature and pH for the α,β-elimination of z-tyrosine were found to be 80℃ and pH 8.0, respectively. The substrate specificity of the enzyme was very broad: L-amino acids including L-tyrosine, 3,4-dihydroxyphenyl-L-alanine (L-DOPA), L-cysteine, L-serine, S-methyl-L-cysteine, β-chloro-L-alanine, and S-(o-nitrophenyl)-L-cysteine all served as substrates. D-Tyrosine and D-serine were also decomposed into pyruvic acid and ammonia at rates of 7 % and 31 % relative to their corresponding L-enantiomers, respectively. D-Alanine, which was inert as a substrate in α,β-elimination, was the only v-amino acid racemized by the enzyme. The K_m values for L-tyrosine, z-DOPA, S-(o-nitrophenyl)-L-cysteine, β-chloro-L-alanine, and S-methyl-L-cysteine were 0.19, 9.9, 0.36, 12, and 5.5 mM, respectively.
Seiji Ishiguro,Hiroaki Onaya,Minoru Esaki,Tomoo Kosuge,Nobuyoshi Hiraoka,Yasunori Mizuguchi,Yasuaki Arai 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.5
We report three cases of mucin-producing carcinoma of the gallbladder, along with the magnetic resonance (MR) findings, especially the findings on a MR cholangiopancreatography. In our cases, linear or curvilinear streaks were detected running along the long axis of an enlarged gallbladder (mucus thread sign). When such findings were seen, a mucin-producing carcinoma of the gallbladder should be included as a differential diagnosis. Thus, gadolinium-enhanced MR imaging is mandatory for the precise diagnosis of the mucin-producing carcinoma of the gallbladder.
A Stereochemical Aspect of Pyridoxal 5'-Phosphate Dependent Enzyme Reactions and Molecular Evolution
JHEE, KWANG-HWAN,YOSHIMURA, TOHRU,KUROKAWA, YOICHI,ESAKI, NOBUYOSHI,SODA, KENJI 한국미생물 · 생명공학회 1999 Journal of microbiology and biotechnology Vol.9 No.6
We have studied the stereospecificities of various pyridoxal 5'-phosphate (PLP) dependent enzymes for the hydrogen transfer between the C-4' of a bound coenzyme and the C-2 of a substrate in the transamination catalyzed by the enzymes. Stereospecificities reflect the structures of enzyme active-sites, in particular the geometrical relationship between the coenzyme-substrate Schiff base and the active site base participating in an α-hydrogen abstraction. The PLP enzymes studied so far catalyze only a si-face specific (pro-S) hydrogen transfer. This stereochemical finding suggests that the PLP enzymes have the same topological active-site structures, and that the PLP enzymes have evolved divergently from a common ancestral protein. However, we found that D-amino acid aminotransferase, branched chain L.-amino acid aminotransferase, and 4-amino-4-deoxychorismate lyase, which have significant sequence homology with one another, catalyze a re-face specific (pro-R) hydrogen transfer. We also showed that PLP-dependent amino acid racemases, which have no sequence homology with any aminotransferases, catalyze a non-stereospecific hydrogen transfer: the hydrogen transfer occurs on both faces of the planar intermediate. Crystallographical studies have shown that the catalytic base is situated on the re-face of the C-4' of the bound coenzyme in D-amino acid aminotransferase and branched chain L-amino acid aminotransferase, whereas the catalytic base is situated on the si-face in other aminotransferases (such as L-aspartate aminotransferase) catalyzing the si-face hydrogen transfer. Thus, we have clarified the stereospecificities of PLP enzymes in relation with the primary structures and three-dimensional structures of the enzymes. The characteristic stereospecificities of these enzymes for the hydrogen transfer suggest the convergent evolution of PLP enzymes.
Lee, Seung-Goo,Hong, Seung-Pyo,Kwak, Mi-Sun,Esaki, Nobuyoshi,Sung, Moon-Hee Korean Society for Biochemistry and Molecular Biol 1999 Journal of biochemistry and molecular biology Vol.32 No.5
Tyrosine phenol-lyase of thermophilic Symbiobacterium sp. SC-1, which is obligately and symbiotically dependent on thermophilic Bacillus sp. SK-1, was purified and characterized. The enzyme is composed of four identical subunits and contains approximately 1 mol of pyridoxal 5'-phosphate (PLP) per mol subunit as a cofactor. The enzyme showed absorption maxima at 330 and 420 nm, and lost this absorption profile by treatment with phenylhydrazine. The apparent dissociation constsnt, $K'_D$, for PLP was determined with the apoenzyme to be about $1.2\;{\mu}M$. The isoelectric point was 4.9. The optimal temperature and pH for the $\alpha,\beta$-elimination of L-tyrosine were found to be $80^{\circ}C$ and pH 8.0, respectively. The substrate specificity of the enzyme was very broad: L-amino acids including L-tyrosine, 3,4-dihydroxyphenyl-L-alanine (L-DOPA), L-cysteine, L-serine, S-methyl-L-cysteine, $\beta$-chloro-L-alanine, and S-(o-nitrophenyl)-L-cysteine all served as substrates. D-Tyrosine and D-serine were also decomposed into pyruvic acid and ammonia at rates of 7% and 31% relative to their corresponding L-enantiomers, respectively. D-Alanine, which was inert as a substrate in a, $\beta$-elimination, was the only D-amino acid racemized by the enzyme. The $K_m$ values for L-tyrosine, L-DOPA, S-(o-nitrophenyl)-L-cysteine, $\beta$-chloro-L-alanine, and S-methyl-L-cysteine were 0.19, 9.9, 0.36, 12, and 5.5 mM, respectively.
Sung, Moon-Hee,Lee, Seung-Goo,Hong, Seung-Pyo,Kwak, Mi-Sun,Nobuyoshi Esaki The Korea Science and Technology Center 1999 BMB Reports Vol.32 No.5
Tyrosine phenol-lyase of thermophilic Symbiobacterium sp. SC-1, which is obligately and symbiotically dependent on thermophilic Bacillus sp. SK-1, was purified and characterized. The enzyme is composed of four identical subunits and contains approximately 1 mol of pyridoxal 5'-phosphate (PLP) per mol subunit as a cofactor. The enzyme showed absorption maxima at 330 and 420nm, and lost this absorption profile by treatment with phenylhydrazine. The apparent dissociation constsnt, K'??, for PLP was determined with the apoenzyme to be about 1.2 μM. The isoelectric point was 4.9. The optimal temperature and pH for the α,β-elimination of L-tyrosine were found to be 80℃ and pH 8.0, respectively. The substrate specificity of the enzyme was very broad: L-amino acids including L-tyrosine, 3,4-dihydroxyphenyl-L-alanine (L-DOPA), L-cysteine, L-serine, S-methyl-L-cysteine, β-chloro-S-alanine, and S-(o-nitrophenyl)-L-cysteine all served as substrates. D-Tyrosine and D-serine were also decomposed into pyruvic acid and ammonia at rates of 7% and 31% relative to their corresponding L-enantiomers, respectively. D-Alanine, which was inert as a substrate in α,β-elimination, was the only D-amino acid racemized by the enzyme. The K?? values for L-tyrosine, L-DOPA, S-(o-nitrophenyl)-L-cysteine, β-chloro-L-alanine, and S-methyl-L-cycsteine were 0.19, 9.9, 0.36, 12, and 5.5 mM, respectively.