Purification and Characterization of Monomeric Isocitrate Dehydrogenase with NADP+-Specificity fromVibrio parahaemolyticusY-4

摘要

NADP+-dependent isocitrate dehydrogenase IDH: EC 1.1.1.42 was purified to electro-phoretic homogeneity fromVibrio parahaemolyticusY-4, and shown to be a monomeric protein of molecular weight 80,000 with a pi of 5.0. The amino acid composition and partial sequence at the N-terminus resembled those reported for other bacterial monomeric IDHs. Immunotitration with antisera to the monomeric and dimeric enzymes (antisera to EDH-II and -I ofVibrioABE-1) showed an immunochemical distinction between the monomeric and dimeric IDHs, but there is similarity within the IDHs of each group. The circular dichroism spectra of the native and heat-denatured enzyme are also similar to those of monomeric IDH (H)H-II ofVibrioABE-1). These monomeric IDHs are proteins comprising 17–22helix and 25–35β-pleated sheet in the native s