CHARACTERIZATION OF KEY GLYCOLYTIC AND OXIDATIVE-ENZYMES IN STEINERNEMA-CARPOCAPSAE

The enzyme activities of isocitrate dehydrogenase (ICDH, NADP-specific ), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), phosphoeno lpyruvate carboxkinase (PEPCK), phosphofructokinase (PFK), pyruvate ki nase (PK), and fructose-1,6-bisphosphatase (FBPase) were studied in th e third-stage juveniles of Steinernema carpocapsae. Reaction requireme nts, pH optima, substrate and cofactor kinetic constants were similar to those reported previously from other parasitic helminths with the e xception of LDH, which was unstable and could not be characterized for specific activity and kinetic constants. The respective pH optima wer e 7.5 for ICDH, 8.8 for MDH, 6.5 for PEPCK, 7.3 for PFK 7.2 for PK, an d 7.5 for FBPase. The specific activities for ICDH, MDH, PEPCK, PFK, P K, and FBPase at pH 7.5 were 4.8, 1,300, 22, 25, 35, and 6.8 (nmoles s ubstrate . min(-1). mg protein(-1)), respectively. In summary, the inf ective juveniles of S. carpocapsae display the metabolism typical of a facultative aerobe.