Efficient carbon dioxide fixation by aromaticcarboxylate decarboxylases catalyzing carboxylation reactions

芳香族羧酸在微生物中的好氧或厌氧降解涉及多种催化氧化或非氧化脱羧反应的酶。近年来，我们发现并鉴定了几种新型的脱羧酶，有效地催化了逆羧化反应。在本研究中，我们调查和特点的2，3和3，4二羟基苯甲酸脱羧酶。将脱羧酶纯化至均一，并研究其理化性质。这两种脱羧酶催化邻苯二酚作为底物的逆羧化反应。对脱羧酶基因进行了克隆和分析。根据一级结构将脱羧酶分为独立的酶组。此外，我们调查了热稳定可逆脱羧酶的应用，酶法二氧化碳固定在超临界二氧化碳。在超临界CO2中，pH变化和温度严重影响脱羧酶的羧化活性。从使用4-羟基苯甲酸作为唯一碳源的富集培养物中，已经分离出具有热稳定的4-羟基苯甲酸脱羧酶的微生物。

Various enzymes catalyzing oxidative or nonoxidative decarboxylation reaction are involved in aerobic or anaerobic degradation of aromatic carboxylic acids in microorganisms. Recently, we found and characterized several kinds of novel decarboxylase, catalyzing the reverse carboxylation reaction efficiently. In the present study, we surveyed and characterized 2,3 and 3,4 dihydroxybenzoate decarboxylases. The decarboxylases were purified to homogeneity, and physicochemicarl properties were investigated. Both dacarboxylases catalyzed the reverse carboxylation reactions for catechol as a substrate. The decarboxylases genes were cloned and analyzed. The decarboxylases were classified into independent enzyme groups on the basis of their primary structures. Furthermore, we surveyed heat stable reversible decarboxylases for the application to enzymatic carbon dioxide fixation in supercritical carbon dioxide. In supercritical carbon dioxide, pH shift and temperature affected the carboxylation activity of decarboxylases severely. From enrichment cultures using 4-hydroxybenzoic acid as a sole carbon source, microorganisms possessing heat-stable 4-hydroxybenzoate decarboxylases have been isolated.