Senior P J, Dawes E A
Biochem J. 1971 Nov;125(1):55-66. doi: 10.1042/bj1250055.
Azotobacter beijerinckii possesses the enzymes of both the Entner-Doudoroff and the oxidative pentose phosphate cycle pathways of glucose catabolism and both pathways are subject to feedback inhibition by products of glucose oxidation. The allosteric glucose 6-phosphate dehydrogenase utilizes both NADP(+) and NAD(+) as electron acceptors and is inhibited by ATP, ADP, NADH and NADPH. 6-Phosphogluconate dehydrogenase (NADP-specific) is unaffected by adenosine nucleotides but is strongly inhibited by NADH and NADPH. The formation of pyruvate and glyceraldehyde 3-phosphate from 6-phosphogluconate by the action of the Entner-Doudoroff enzymes is inhibited by ATP, citrate, isocitrate and cis-aconitate. Glyceraldehyde 3-phosphate dehydrogenase is unaffected by adenosine and nicotinamide nucleotides but the enzyme is non-specific with respect to NADP and NAD. Citrate synthase is strongly inhibited by NADH and the inhibition is reversed by the addition of AMP. Isocitrate dehydrogenase, a highly active NADP-specific enzyme, is inhibited by NADPH, NADH, ATP and by high concentrations of NADP(+). These findings are discussed in relation to the massive synthesis of poly-beta-hydroxybutyrate that occurs under certain nutritional conditions. We propose that synthesis of this reserve material, to the extent of 70% of the dry weight of the organism, serves as an electron and carbon ;sink' when conditions prevail that would otherwise inhibit nitrogen fixation and growth.
拜氏固氮菌拥有葡萄糖分解代谢的恩特纳-杜德洛夫途径和氧化戊糖磷酸循环途径的酶，并且这两条途径都受到葡萄糖氧化产物的反馈抑制。别构葡萄糖6-磷酸脱氢酶既利用NADP(+)又利用NAD(+)作为电子受体，并受到ATP、ADP、NADH和NADPH的抑制。6-磷酸葡萄糖酸脱氢酶（NADP特异性）不受腺苷核苷酸的影响，但受到NADH和NADPH的强烈抑制。由恩特纳-杜德洛夫酶的作用将6-磷酸葡萄糖酸转化为丙酮酸和3-磷酸甘油醛受到ATP、柠檬酸、异柠檬酸和顺乌头酸的抑制。3-磷酸甘油醛脱氢酶不受腺苷和烟酰胺核苷酸的影响，但该酶对NADP和NAD是非特异性的。柠檬酸合酶受到NADH的强烈抑制，添加AMP可逆转这种抑制作用。异柠檬酸脱氢酶是一种高活性的NADP特异性酶，受到NADPH、NADH、ATP以及高浓度NADP(+)的抑制。结合在某些营养条件下发生的聚-β-羟基丁酸酯的大量合成对这些发现进行了讨论。我们提出，这种储备物质的合成占生物体干重的70%，在否则会抑制固氮作用和生长的条件占主导时，作为电子和碳的“汇”。
