炭酸固定発酵に関する研究 : (第11報) Schizophyllum communeにおける尿素およびオルトリン酸のL-Malic acid生成促進効果の酵素化学意義

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It was previously reported that orthophosphate, CaCO_3 and urea were limiting factors for the L-malate production by CO_2-fixing fermentation using Schizophyllum commune under culture conditions. By using the homogenate of the mold, L-malate was formed from glucose, 3-phosphoglycerate and pyruvate in presences of orthophosphate and KHCO_3,where glucose was most effective as the substrate, and the higher concentration orthophosphate inhibited the L-malate formation from pyruvate, but it did not inhibite from 3-phosphoglycerate. Therefore, L-malate would not be formed through the oxidative process such as TCA cycle and glyoxylate bypath. By using the cell-free extract of the mold, it was also revealed that the inhibitory effect of orthophosphate on the oxaloacetate formation from pyruvate was reduced by the addition of ATP. On the contrary, the oxaloacetate formation from 3-phosphoglycerate was markedly stimulated by the addition of both of orthophosphate and KHCO_3. The formation from phosphoenolpyruvate was much more stimulated by them. In these experiments, it was shown that the effect of urea was resembled to that of KHCO_3. The optimum concentration of orthophosphate added was 0.4 and 0.8 mM in KHCO_3 and urea containing system, respectively.Consequently, both of the occurrences of pyruvate carboxylase- and phosphoenolpyruvic carboxytransphosphorylase-like enzymes seemed to be observed in the extract, while the latter reaction was expected to be more active than the former in the CO_2-fixing fermentation because of the latter's superiority in bioenergetics as shown in equation (3) and (4).In many cases, it was shown that the pyruvate formation was parallel to the oxaloacetate formation. The phenomenon seems to be explained by an unknown enzyme which produces pyruvate from phosphoenolpyruvate accepting its phosphate on orthophosphate, but, on the other hand, it can be reasonably understood by the phosphoenolpyruvic carboxytransphosphorylase followed by oxaloacetate decarboxylation.
1967-11-25

炭酸固定発酵に関する研究 : (第11報) Schizophyllum communeにおける尿素およびオルトリン酸のL-Malic acid生成促進効果の酵素化学意義

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