Endogenous and recombinant human His-cofilin has an intracellular disulphide bond.

A) Recombinant human His-cofilin, platelet, and endothelial cell lysates were subjected to SDS-PAGE under reducing (with ß-mercapto-ethanol; +ßM) and non-reducing conditions (without ß-mercapto-ethanol; -ßM) and then immunoblotted with anti-cofilin antibody. Monomeric cofilin showed higher electrophoretic mobility under non-reducing conditions than under reducing conditions. Moreover, oligomers of different molecular masses of recombinant His-cofilin but not of endogenous cofilin were observed under non-reducing condition, suggesting the involvement of intermolecular disulphide bonding in in vitro oligomerization. B) Recombinant human cofilin (with and without His-tag) were subjected to SDS-PAGE under reducing and non-reducing conditions and analyzed by Coomassie blue staining. Both types of recombinant cofilin demonstrate a higher electrophoretic mobility under non-reducing conditions as compared to reducing conditions.