Site directed mutagenesis to probe for active site components of liver mitochondrial aldehyde dehydrogenase.

Mutational analysis allowed us to rule out an essential role for the histidine residues and for serine 74 in mammalian aldehyde dehydrogenase. The later though, was found to be important in coenzyme interaction. The function of the serine could not be replaced by threonine or by cysteine. The absolute requirement for cysteine 302 and for glutamate 268 was verified using mutational analysis. The fact that these two residues are completed conserved among all aldehyde dehydrogenases is consistent with their being essential in the catalytic process.