Isolation and characterization of secretory actin . DNAase I complex from rat pancreatic juice.

DNAase I isolated from rat pancreatic juice was always found in association with a protein of molecular weight 43 000. This association leads to inhibition of the isolated rat pancreatic DNAase I activity by 66%. The molecular weight of the complex was found to be 74 000 by gel filtration indicating a 1 : 1 molar association of both proteins. Since the protein of molecular weight 43 000 has a number of properties similar to skeletal muscle actin such as filament formation, nucleotide binding, inhibition of the rat pancreatic DNAase I activity and comigration with skeletal muscle actin on polyacrylamide gels in the presence of dodecylsulfate, it is concluded that DNAase I is bound to actin in rat pancreatic juice in a 1 : 1 complex. It is demonstrated that a protein fraction from bile is able to activate the DNAase I enzymatic activity of the rat secretory actin . DNAase I complex.