Effects of plumbous ion on guanine metabolism

Abstract

The enzyme guanine aminohydrolase (guanase) is inhibited by low levels of Pb 2+. The inhibition is noncompetitive and the K i is 3.0 × 10 -6 M. The only other heavy metals that are inhibitory at low concentrations are Ag +, which is 36% more, and Hg 2+, which is about 50% less inhibitory than Pb 2+. The inhibition of guanase by Ph 2+ and Hg 2+ is synergistic and the inhibition of the enzyme was readily reversed by EDTA. The relationship of these studies with guanase and to the etiology and treatment of saturnine gout, which appears in humans suffering from lead poisoning, is discussed.