Higa A I, Massarini E, Cazzulo J J
Rev Asoc Argent Microbiol. 1976 May-Aug;8(2):74-81.
A comparative study of the citrate synthases purified from the facultatively photosynthetic bacterium Rhodospirillum rubrum (Gram negative) and the thermophile Bacillus stearothermophilus (Gram positive) was made. The citrate synthase from R. rubrum was activated by KCl (6-fold at 0.1 M KCl) and, less effectively, by NaCl and NH4Cl. Its molecular weight was about 300,000. The enzyme was strongly inhibited by NADH, and this inhibition was counteracted by AMP. The citrate synthase from B. stearothermophilus was little affected by KCl, NaCl and NH4Cl, all of which activated by about 25% at 0.1 M. Its molecular weight was ca 100,000. The enzyme was not affected by NADH or AMP. Both citrate synthases were insensitive to alpah-oxoglutarate concentrations up to 5 mM, and were inhibited by ATP; the B. stearothermophilus enzyme was more strongly inhibited than the R. rubrum enzyme. In both cases the ATP inhibition was strictly competitive towards acetyl-CoA and non-competitive towards oxaloacetate. Both enzymes, in spite of the peculiar physiological properties of their bacterial sources, followed the close correlation between the properties of the citrate synthase and the taxonomical position of the microorganism, proposed by Weitzman and his co-workers.
对从兼性光合细菌深红红螺菌（革兰氏阴性）和嗜热脂肪芽孢杆菌（革兰氏阳性）中纯化得到的柠檬酸合酶进行了比较研究。深红红螺菌的柠檬酸合酶被KCl激活（在0.1 M KCl时激活6倍），被NaCl和NH4Cl激活的效果较差。其分子量约为300,000。该酶受到NADH的强烈抑制，而这种抑制可被AMP抵消。嗜热脂肪芽孢杆菌的柠檬酸合酶受KCl、NaCl和NH4Cl的影响较小，在0.1 M时这三种物质均使其活性提高约25%。其分子量约为100,000。该酶不受NADH或AMP的影响。两种柠檬酸合酶对高达5 mM的α-酮戊二酸浓度均不敏感，并受到ATP的抑制；嗜热脂肪芽孢杆菌的酶比深红红螺菌的酶受到的抑制更强。在这两种情况下，ATP的抑制作用对乙酰辅酶A严格呈竞争性，对草酰乙酸呈非竞争性。尽管这两种酶的细菌来源具有独特的生理特性，但它们都符合韦茨曼及其同事提出的柠檬酸合酶特性与微生物分类地位之间的密切相关性。
