The specificity of carboxyl group modification during the inactivation of the Escherichia coli F1-ATPase with dicyclohexyl[14C]carbodiimide.

Abstract

When the Escherichia coli F1-ATPase (EFI) is inactivated with dicy~lohexyl[~~C]carbodiirnide and then gelfiltered, about 1 g atom of I4C is bound per mol of enzyme.However, only 45% of this radioactivity remained bound to the protein when the subunits were isolated in the presence of 8 M urea.The majority of the radioactivity which remained bound to the protein during subunit isolation was associated with the p subunit that contained 0.13 g atom of I4C per mol.A tryptic peptide derived from the labeled p subunit was isolated which contained the majority of the radioactivity bound to it.Based on the amino acid composition of this peptide, the amino acid compositions of radioactive fragments derived from it, and the amino acid sequence of the / 3 subunit of EFl translated from the gene (Sar-