Effects of anesthetics and dichlorodifluoromethane on the activities of glyceraldehyde-phosphate dehydrogenase and pectin methylesterase.

Solutions of glucose-3-phosphate dehydrogenase (GPD) and pectin methylesterase (PME) were exposed to various anesthetics and dichlorodifluoromethane (F-12) to determine the abilities of these chemicals to inhibit enzyme activity. An aqueous solution of PME was exposed to saturation levels of the test chemicals for 30 min at 21 degrees. All test chemicals were inhibitory (measured after release of the test chemical) with propane being most inhibitory followed in order by F-12, cyclopropane, Ethrane (F2HCOF2CCHClF) and halothane (CF3CHClBr). GPD was exposed to various concentrations of F-12 and halothane for various times at 0 degrees and 33 degrees. Halothane at 33 degrees and a saturation concentration reduced the initial reaction velocity of GPD to zero after a 10-min exposure period. F-12 was somewhat less inhibitory than halothane, but inhibition in all instances was irreversible. Halothane was found to affect the circular dichroism and optical rotary dispersion spectra of GPD, with the magnitude of the changes generally increasing with treatment time. The observed changes were believed to arise from side-chain transitions of GPD.