Inactivation of Saccharomyces cerevisiae glucose-6-phosphate dehydrogenase by diethylpyrocarbonate.
Glucose-6-phosphate dehydrogenase purified from Saccharomyces cerevisiae is rapidly inactivated by diethylpyrocarbonate at pH 6.8 and 30 degrees C with a concomitant increase in absorbance at 242 nm. The second-order rate constant for inactivation was calculated to be 487.8 M-1 min-1. The pH dependence of inactivation suggests the involvement of an amino acid residue having a pKa of 6.77. These results indicate that the inactivation is due to the modification of a histidine residue(s). In the presence of substrate, glucose-6-phosphate or NADP+, the rate of inactivation is decreased, indicating that the essential histidine residue(s) is located at the active site, possibly at the region of overlap of substrates at the binding site.
Kim
Y S
YS
Department of Biochemistry, College of Science, Yonsei University, Seoul, Korea.
Kim
Y I
YI
Byun
H S
HS
D002384:Catalysis; D004047:Diethyl Pyrocarbonate / Q000494:pharmacology*; D005561:Formates / Q000494:pharmacology*; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors*; D006639:Histidine / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D005561:Formates; D006639:Histidine; D005954:Glucosephosphate Dehydrogenase; D004047:Diethyl Pyrocarbonate