Partial Purification and Properties of 3-Phosphoglycerate Dehydrogenase in the Fat Body Tissues of Larvae of the Silkworm, Bombyx mori (Lepidoptera : Bombycidae)

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A high activity of 3-phosphoglycerate dehydrogenase (E.C. 1.1.1. 95) was detected in the fat body tissues, midgut and silkglands of the silkworm, Bombyx mori, and the enzyme activity was the higherst in the fat body tissues. The enzyme activity was concentrated in the supernatant fraction obtained by centrifugation at 15,000 g for 30 min, while a low activity of the enzyme was observed in the mitochondrial fraction. 3-Phosphoglycerate dehydrogenase was partially purified from the homogenate of the fat body tissues by column chromatography on DE_<52>-cellulose and Ultrogel AC_<34>, and the final partial purification was approximately 60-fold. The pH optimum for the enzyme reaction was 7.5,and the isoelectric point of the enzyme corresponded to pH 7.0. The K_m values were 1.1×10^<-4> M for hydroxypyruvate phosphate and 3.6×10^<-6> M for NADH, respectively.It is possible to substitute NADH with NADPH as a coenzyme for 3-phosphoglycerate dehydrogenase. The crude homogenate of the fat body showed a weak activity of the enzyme which promoted the reduction of hydroxypyruvate, but the partially purified preparation lost such activity. The participation of 3-phosphoglycerate dehydrogenase in the synthesis of serine and glycine for the silk-protein in this insect was briefly discussed.
日本応用動物昆虫学会の論文
1985-08-25