Ammonium Sulfate Activation of Phosphodiesterase in Homogenates of Larvae of the European Corn Borer

Abstract

Summary

European corn borer phosphodiesterase is highly activated by (NH₄)₂SO₄ and moderately activated by NH₄Cl (pH 7.6, 33°). Vertebrate and crayfish diesterases, on the other hand, are inhibited by (NH₄)₂SO₄. It is likely that (NH₄)₂SO₄ causes some configurational change in the European corn borer phosphodiesterase molecule which results in the exposure of more active sites and hence greater enzyme activity. In in vitro tests caffeine (0.008 M) and theophylline (0.008 M) inhibit phosphodiesterase more effectively in European corn borer larvae than in crayfish, ovine, bovine, or rat tissue.