Inhibition of deoxyribonuclease i activity by actin covalently cross-linked to chick brain actin depolymerizing factor through exposed sulfhydryls

All but one of the six free sulfhydryl groups of chick brain actin depolymerizing factor (ADF) are protected from modification when ADF forms a 1:1 complex with actin. This exposed sulfhydryl can be cross-linked to cys 374 of actin with N,N′-phenylenedimaleimide. The cross-linked complex inhibits the hydrolytic activity of pancreatic deoxyribonuclease (DNase I) to an identical extent as both the untreated complex and an equivalent amount of free actin. These data indicate that ADF binds to actin at a site which does not overlap with the DNase I binding site.