Turnover of Genetically Defined Catalase Isozymes in Maize

Abstract

The turnover of two homotetramers of catalase, V⁴ and Z⁴, specified by genes at two separate loci, has been studied during germination of maize seed by the techniques of density labeling and starch-gel electrophoresis. Both isozymes were shown to be turning over during this time. However, Z⁴ accumulates because the rate of synthesis exceeds the rate of degradation, whereas V⁴ slowly disappears because the rate of degradation exceeds the rate of synthesis. Evidence is also presented that the rate of synthesis of Z⁴ exceeds that of V⁴, which suggests that this may be a major factor in the differential expression of the two catalase genes.

• density labeling
• synthesis
• degradation
• starch-gel electrophoresis