Tabita R, Lundgren D G
J Bacteriol. 1971 Oct;108(1):343-52. doi: 10.1128/jb.108.1.343-352.1971.
Glucose-6-phosphate dehydrogenase was partially purified from both glucose-grown and iron-glucose-grown Thiobacillus ferrooxidans. The enzyme possesses a dual nucleotide specificity for either nicotinamide adenine dinucleotide phosphate (NADP) or nicotinamide adenine dinucleotide (NAD) and has a molecular weight of 110,000 as determined by gel electrophoresis. Evidence is presented that T. ferrooxidans glucose-6-phosphate dehydrogenase is identical when isolated from cells grown mixotrophically (iron-glucose grown) or cells grown heterotrophically (glucose-grown cells). The enzyme is activated by Mg(2+), and to a lesser extent by low concentrations of Mn(2+). Reduced NAD inhibits the enzyme from T. ferrooxidans. No deviation from normal Michaelis-Menten kinetics was observed in velocity versus substrate concentration experiments. Adenosine triphosphate exerted a profound inhibition of the enzyme; the effect was 10 times more pronounced in the presence of NAD as compared to NADP. The physiological significance of this inhibition is discussed.
从以葡萄糖为碳源生长的氧化亚铁硫杆菌和以铁-葡萄糖为碳源生长的氧化亚铁硫杆菌中部分纯化出了6-磷酸葡萄糖脱氢酶。该酶对烟酰胺腺嘌呤二核苷酸磷酸（NADP）或烟酰胺腺嘌呤二核苷酸（NAD）具有双重核苷酸特异性，通过凝胶电泳测定其分子量为110,000。有证据表明，从混合营养生长（铁-葡萄糖生长）的细胞或异养生长（葡萄糖生长的细胞）中分离出的氧化亚铁硫杆菌6-磷酸葡萄糖脱氢酶是相同的。该酶被Mg(2+)激活，在较低程度上也被低浓度的Mn(2+)激活。还原型NAD抑制氧化亚铁硫杆菌的该酶。在速度与底物浓度实验中未观察到偏离正常米氏动力学的情况。三磷酸腺苷对该酶有显著抑制作用；与NADP相比，在有NAD存在时这种作用更为明显，是其10倍。讨论了这种抑制作用的生理意义。
