A comparison of the effects of cyanide, hydrogen peroxide, and phenylglyoxal on eucaryotic and procaryotic Cu,Zn superoxide dismutases.

The Cu,Zn superoxide dismutases from bovine liver, yeast, Caulobacter crescentus, and Photobacter leiognathi were compared for their susceptibilities to inhibition by cyanide and to inactivation by hydrogen peroxide and phenylglyoxal. All of these enzymes were affected by these reagents, albeit with some differences in sensitivity. The yeast and the bacterial enzymes were thus more sensitive to cyanide than was the bovine enzyme, while the bovine and the yeast enzymes were inactivated more rapidly by hydrogen peroxide and less rapidly by phenylglyoxal than were their bacterial counterparts. The qualitative similarities in the behavior of all of these enzymes suggest overriding similarities in their active site regions. However, a quantitative comparison of the data suggests that the bacterial enzymes are more like each other than they are like the eucaryotic enzymes, and furthermore, are more like the yeast enzyme than the bovine enzyme.