Sokatch J R, Burns G
Arch Biochem Biophys. 1984 Feb 1;228(2):660-6. doi: 10.1016/0003-9861(84)90036-5.
Pseudomonas putida produces two lipoamide dehydrogenases with molecular weights of 49,000 and 56,000 designated LPD-val and LPD-glc, respectively. LPD-val is required for oxidation of valine, since it is specifically utilized as the E3 component of branched-chain keto acid dehydrogenase. Since glycine oxidation by bacteria and mammals also requires lipoamide dehydrogenase, we desired to determine which lipoamide dehydrogenase would be used by the P. putida glycine oxidation system. When grown in a medium with glycine as the sole nitrogen source, P. putida produced a single lipoamide dehydrogenase with a molecular weight of 56,000 and which reacted with antiserum to LPD-glc. The partially purified glycine oxidation system from P. putida was stimulated by LPD-glc but not by LPD-val and was inhibited by anti-LPD-glc, but not by anti-LPD-val. It was not possible to detect LPD-val in extracts of cells grown in glucose-glycine medium by the use of anti-LPD-val. LPD-glc was five times as active as LPD-val in catalyzing the oxidation of purified protein H, the heat-stable, lipoic acid-containing protein of the glycine oxidation system. These results indicate that LPD-glc is specifically utilized for glycine oxidation in P. putida.
恶臭假单胞菌产生两种分子量分别为49,000和56,000的硫辛酰胺脱氢酶，分别命名为LPD-val和LPD-glc。LPD-val是缬氨酸氧化所必需的，因为它被特异性地用作支链酮酸脱氢酶的E3组分。由于细菌和哺乳动物的甘氨酸氧化也需要硫辛酰胺脱氢酶，我们希望确定恶臭假单胞菌的甘氨酸氧化系统会使用哪种硫辛酰胺脱氢酶。当在以甘氨酸作为唯一氮源的培养基中生长时，恶臭假单胞菌产生一种分子量为56,000的单一硫辛酰胺脱氢酶，它能与抗LPD-glc血清发生反应。来自恶臭假单胞菌的部分纯化的甘氨酸氧化系统受到LPD-glc的刺激，但不受LPD-val的刺激，并且被抗LPD-glc抑制，但不被抗LPD-val抑制。通过使用抗LPD-val，在葡萄糖 - 甘氨酸培养基中生长的细胞提取物中无法检测到LPD-val。在催化甘氨酸氧化系统中热稳定的含硫辛酸的蛋白质——纯化蛋白H的氧化时，LPD-glc的活性是LPD-val的五倍。这些结果表明，LPD-glc在恶臭假单胞菌中被特异性地用于甘氨酸氧化。
