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Molecular Characterization of Reversible Decarboxylases Catalyzing CO_2 Fixation and Their Application to Molecular Conversion Process

催化CO_2固定的可逆脱羧酶的分子表征及其在分子转化过程中的应用

基本信息

批准号：
14560061
负责人：
YOSHIDA Toyokazu
金额：
$ 2.37万
依托单位：
Gifu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Generally, decarboxylases can not catalyze the reverse carboxylation reaction. However, we found novel decarboxylases efficiently catalyzing nonoxidative decarboxyation. In the metabolism of phenol in the absence of oxygen, 4-hydroxybenzoate decarboxylase found to catalyze carbon dioxide fixation. In the view point of application to chemical industry, the reversible decarboxylases are useful for the synthesis of aromatic carboxylic acids, because a carboxyl group is regioselectively introduced into aromatic ring. In the present research, we screened novel decarboxylases reversibly catalyzing nonoxidative decarboxylation, revealed physicochemical and molecular characteristics, and evaluated the reverse carboxylation activities.The primary structures of pyrrole-2-carboxylate decarboxylase and indole-3carboxylate decarboxylase were determined from their gene analysis. These decarboxylases showed similarity to various microbial hypothetical proteins. In the screening of 4-hydroxybenzoate decarboxylase, the enzyme activity was widely detected in various bacteria, actinomycetes and yeasts, contrary to the previous observation. As for 2,6-dihydroxybenzoate decarboxylase, a novel decarboxylase, the efficient regioselecetive carboxylation of 1,3-dihydroxybenzene was confirmed in the presence of KHCO_3. From the analyses for enzymatic properties and structures, various reversible decarboxylase were classified into two subgroups.

通常，脱羧酶不能催化逆羧化反应。然而，我们发现新的脱羧酶有效地催化非氧化脱羧。在苯酚代谢过程中，在无氧条件下，发现4-羟基苯甲酸脱羧酶催化二氧化碳固定。从应用于化学工业的观点来看，可逆脱羧酶可用于合成芳香族羧酸，因为羧基被区域选择性地引入芳香环中。本研究筛选了新的可逆催化非氧化脱羧的脱羧酶，并对其理化和分子特性进行了研究，同时对吡咯-2-羧酸脱羧酶和吲哚-3-羧酸脱羧酶进行了基因分析，确定了它们的一级结构。这些脱羧酶显示出与各种微生物假设蛋白的相似性。在4-羟基苯甲酸脱羧酶的筛选中，发现该酶在各种细菌、放线菌和酵母菌中都有广泛的活性，与以往的观察相反。2，6-二羟基苯甲酸脱羧酶是一种新的脱羧酶，在KHCO_3存在下，对1，3-二羟基苯具有高效的区域选择性羧化作用。通过对酶性质和结构的分析，将各种可逆脱羧酶分为两个亚类。