The use of sodium dodecylsulphate-acrylamide-gel electrophoresis to analyse trypsin preparations

Abstract

Soybean trypsin inhibitor covalently attached to Sepharose (STI-Sepharose) was used to remove inactive, low molecular weight contaminants from commercial samples of trypsin. The remaining material (eluted at pH 2 from the STI-Sepharose) contained 97–99% active trypsin but was shown to be heterogeneous by sodium dodecylsulphate-acrylamide-gel electrophoresis. This method demonstrated the presence of both β-trypsin (with an intact polypeptide chain) and α-trypsin (with the Lys 131-Ser 132 bound cleaved). The results of gel electrophoresis could be used to provide a simple, reliable determination of the relative amounts of the two forms of trypsin, with some advantages over previous methods.