COMPARISON OF CU,ZN-SUPEROXIDE DISMUTASES OF CLAWED FROGS OF THE GENUS XENOPUS

Isoenzyme profiles and thermal stability of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) of clawed frogs of genus Xenopus (X. laevis and X. boreal is) were compared. Earlier the presence of an unusually thermolabile m utant Cu,Zn-SOD as well as normal enzyme was shown in X. laevis. Havin g confirmed the data, we further show that X. borealis contains only t he thermolabile Cu,Zn-SOD. This suggested that a mutation in the Cu,Zn -SOD gene and genome duplication have occurred in the immediate predec essor of X. laevis. Later on the parent Cu,Zn-SOD gene was lost, leavi ng only the mutated form of Cu,Zn-SOD in X. borealis.