Bovine seminal plasmin is a DNA unwinding protein

Abstract

The duplex DNA unwinding ability of seminal plasmin from bovine semen was examined by treatment of plasmid-protein complexes with calf thymus topoisomerase I and resolution of the topoisomer distributions by agarose gel electrophoresis. Binding of seminal plasmin results in a moderate degree of unwinding of supercoiled plasmid. The elongation of the RNA chain by E.coli RNA polymerase over promoter containing template is not inhibited by seminal plasmin. However, the reinitiation of transcription is blocked in such cases indicating that seminal plasmin inhibits transcription by binding to the initiation site of RNA polymerase.