[Protaminase activity of plasma and serum in vitro. II.- Electrophoretic study of serum albumin-protamine soluble complexes].

Cellulose acetate electrophoresis (pH 8,6 ionic strength 0,05) puts in evidence the soluble complexes "albumin-protamine" which are easily distinguished from albumin being more positively charged. The albumin-protamine complexes formed in serum or plasma, after addition of protamine, undergo in vitro a dissociation progressing with time to the complete restitution of albumin. This dissociation is slowed down by the inhibitors of the carboxypeptidase B (SCPB), an enzyme present in plasma and serum, but is not influenced by the inhibitor phenylmethyl-sulfonyl fluoride (PMSF). A protamine which had lost its four C-terminal arginines by the action of a DFP-treated carboxypeptidase B (CPB) still formed complexes with albumin (and, besides, remained able to neutralize heparin). On the contrary protamine degraded first by CPB, and afterwards by the DFP-treated carboxypeptidase A (CPA) lost these two properties. These results suggest that the dissociation of albumin-protamine complex in plasma and serum requires a protaminase action additional to the action of SCPB.