Menzel K, Zeng A P, Deckwer W D
GBF-Gesellschaft für Biotechnologische Forschung, Biochemical Engineering Division, Braunschweig, Germany.
J Biotechnol. 1997 Aug 11;56(2):135-42. doi: 10.1016/s0168-1656(97)00110-7.
Stoichiometric analysis of pathways involved in anaerobic bioconversion of glycerol by Klebsiella pneumoniae revealed that enzyme(s) in addition to pyruvate formate-lyase (PFL) must be involved in pyruvate decarboxylation. In this work, enzymatic evidence is presented that confirmed a simultaneous involvement of pyruvate dehydrogenase complex (PDH) and excluded the presence of pyruvate:ferredoxin oxidoreductase in this anaerobic bioprocess. The in vitro PDH activity of cell extract from continuous culture was found to be strongly affected by the substrate (glycerol) concentration in medium and cell growth rate (dilution rate). It increases with increasing glycerol concentration and correlates well with the specific substrate uptake rate at different dilution rates in a kind of saturation function. At a similar substrate uptake rate, it decreases with cell growth rate. The in vitro activity of PDH is much higher than its in vivo activity calculated from the pathway stoichiometry but comparable to the calculated in vivo activity of PFL.
肺炎克雷伯菌对甘油进行厌氧生物转化所涉及途径的化学计量分析表明，除丙酮酸甲酸裂解酶（PFL）外，必定还有其他酶参与丙酮酸脱羧反应。在本研究中，给出了酶学证据，证实丙酮酸脱氢酶复合体（PDH）同时参与其中，并排除了丙酮酸：铁氧化还原蛋白氧化还原酶在该厌氧生物过程中的存在。连续培养的细胞提取物的体外PDH活性受培养基中底物（甘油）浓度和细胞生长速率（稀释率）的强烈影响。它随甘油浓度的增加而增加，并且在不同稀释率下与特定底物摄取速率以一种饱和函数的形式呈现出良好的相关性。在相似的底物摄取速率下，它随细胞生长速率降低。PDH的体外活性远高于根据途径化学计量学计算出的其体内活性，但与计算出的PFL体内活性相当。
