The appearance of enzyme activity for D-amino acid in highly concentrated ammonium phosphate solution

高浓度磷酸铵溶液中D-氨基酸酶活性的表现

• 批准号: 06680551
• 负责人: SHIMADA Akihiko
• 金额: $ 0.77万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06680551/
• 关键词: origin of optical activity; selection mechanism for optical isomers on enzyme; D-tryptophan; tryptophanase; diammoniumhydrogen phosphate; 光学活性の起源; リン酸水素2アンモニウム; 生命の起原; アミノ酸光学異性体の選択

We had elucidated the reaction pathway of tryptophanase-catalysed degradation of D-tryptophan in the presence of diammoniumhydrogen phosphate and had studied selection mechanism of D-amino acids on enzyme for the term of this project. Information newly obtained from this research is described below.1.Diammoniumhydrogen phosphate ((NH_4) _2HPO_4) acted on tryptophanase as an activator below 50% saturation, but as a noncompetitive inhibitor above 50% saturation.2.Reaction pathway was satisfactorily clarified on the basis of kinetic analysis. Tryptophanase bound at random with D-tryptophan and (NH_4) _2HPO_4 in rapid equilibrium. D-tryptophan was degraded through tryptophnase・D-tryptophan・ (NH_4) _2HPO_4 complex.3.D-tryptophan bound with tryptophanase in the absence of (NH_4) _2HPO_4. Increasing concentration of (NH_4) _2HPO_4 changed inhibition type from competitive type through mixed type to uncompetitive type.4.The above result indicated that binding site and catalytic site within active site of tryptophanase was independent. In addition, it was suggested that the binding site of D-tryptophan independently behaved for that of L-tryptophan.5.Results so far obtained have been reported in papers.

本课题主要研究了磷酸氢二铵存在下D-色氨酸酶催化降解D-色氨酸的反应途径，并研究了D-氨基酸对酶的选择机理。本研究获得的新结果如下：1.磷酸氢二铵（（NH_4）_2HPO_4）在50%饱和度以下对酶有激活作用，而在50%饱和度以上对酶有非竞争性抑制作用。色氨酸酶与D-色氨酸和（NH_4）_2HPO_4随机结合，迅速平衡。D-色氨酸通过色氨酸酶·D-色氨酸·（NH_4）_2HPO_4复合物降解。随着（NH_4）_2HPO_4浓度的增加，抑制类型由竞争型、混合型变为非竞争型。另外，D-色氨酸的结合位点与L-色氨酸的结合位点是独立的。

项目成果

島田秋彦: "トリプトファナーゼのD-トリプトファンに対する反応機構の動力学的解析" Viva Origino. 23. 169-178 (1995)

Akihiko Shimada：“色氨酸酶对 D-色氨酸反应机制的动态分析”Viva Origino 23. 169-178 (1995)。

島田秋彦: "Reaction mechanism to D-tryptophan in tryptopanase" Amino Acids. 9. 24-24 (1995)

Akihiko Shimada：“色氨酸酶中 D-色氨酸的反应机制”《氨基酸》9. 24-24 (1995)。

島田 秋彦: "Tryptophanase-catalysed degradation of D-tryptophan in highly concentrated diammonium hydrogen phosphate solution" Amino Acids. 11. 83-89 (1996)

Akihiko Shimada：“高浓度磷酸氢二铵溶液中色氨酸酶催化的 D-色氨酸降解”氨基酸。 11. 83-89 (1996)

島田秋彦: "トリプトファナーゼにおけるD-トリプトファンの活性部位の反応速度論による検討" Viva Origino. (印刷中). (1997)

Akihiko Shimada：“色氨酸酶中 D-色氨酸活性位点的动力学研究”Viva Origino（出版中）。

島田 秋彦: "Reaction Pathway of tryptophanase degrading D-tryptophan" Amino Acids. (印刷中). (1997)

Akihiko Shimada：“色氨酸酶降解 D-色氨酸的反应途径”（正在出版）。