Suzuki S, Takeuchi Y, Sasaki K, Katsuki H
J Biochem. 1976 Oct;80(4):867-74. doi: 10.1093/oxfordjournals.jbchem.a131349.
Studies on threo-beta-methylmalate metabolism in a soil bacterium of the genus Bacillus which can utilize threo-beta-methylmalate as a sole carbon source were carried out. When DL-threo-beta-methylmalate was incubated with a cell-free extract of the bacterium, citramalate was found to be formed. Similarly, formation of threo-beta-methylmalate from DL-citramalate was confirmed. These dicarbosylic acids were identified by gas chromatography-mass spectrometry. Examination of inducibility, substrate specificity, and cofactor requirement of the enzymes involved in the reactions showed the existence of two interconversion reactions between the threo-beta-methylmalate and citramalate. One was an interconversion reaction between L-threo-beta-methylmalate and L-citramalate via mesaconate and the other was an interconversion reaction between D-threo-beta-methylmalate and D-citramalate via citraconate. These reactions were both reversible and were catalyzed by distinct and inducible enzymes. It is suggested that the two reactions participate in the catabolism of threo-beta-methylmalate.
对一种能将苏式-β-甲基苹果酸作为唯一碳源利用的芽孢杆菌属土壤细菌中的苏式-β-甲基苹果酸代谢进行了研究。当将DL-苏式-β-甲基苹果酸与该细菌的无细胞提取物一起温育时，发现生成了柠苹酸。同样，也证实了由DL-柠苹酸生成苏式-β-甲基苹果酸。这些二元羧酸通过气相色谱-质谱法进行了鉴定。对反应中所涉及酶的诱导性、底物特异性和辅因子需求的研究表明，在苏式-β-甲基苹果酸和柠苹酸之间存在两种相互转化反应。一种是L-苏式-β-甲基苹果酸和L-柠苹酸通过中康酸的相互转化反应，另一种是D-苏式-β-甲基苹果酸和D-柠苹酸通过柠康酸的相互转化反应。这些反应都是可逆的，且由不同的可诱导酶催化。提示这两种反应参与了苏式-β-甲基苹果酸的分解代谢。
