Kinetics of inhibition and hysteresis of sheep liver cytoplasmic aldehyde dehydrogenase with glyoxylic acid: further evidence relating to the two-site model for aldehyde oxidation.

摘要: Abstract Despite the fact that it is an aldehyde, glyoxylic acid not a substrate for sheep liver cytoplasmic aldehyde dehydrogenase; instead functions as inhibitor of both esterase and dehydrogenase activities. From consideration inhibition patterns concluded does bind in catalytic propionaldehyde-binding domain, thus confirming two-site model proposed previously. Since corresponding neutral methyl ester suggested binding domain must contain negatively charged group which prevents acid. Steady-state pre-steady-state kinetic studies indicate inhibits activity by converting enzyme into dead-end form cannot undergo catalytically essential conformational change. Incubation with NAD + 10 min before addition propionaldehyde gave rise to hysteresis effects can be explained on basis slow isomerization · complex.