Thioprenols as hydrazinolysis products of prenylated proteins: dependence upon methylation of the prenylcysteine.

When prenylated proteins are treated with hydrazine at elevated temperatures, a substantial fraction of the prenylcysteines are cleaved at the C-S bond of the beta-carbon of cysteine. Thioprenols, the initial products of this reaction, are then reduced, over time, to hydrocarbons. This elimination reaction is favored several fold if the prenylcysteine is present as a carboxylate derivative rather than as a carboxyl terminal free amino acid. Thus, the pattern of elimination has the potential for detecting substitution (methylation) of prenylcysteines. In addition, the formation of thioprenols leads to more sensitive ways for determination of the prenylcysteines.