The Basic Trypsin Inhibitor of Bovine Pancreas

Partial reduction of the basic pancreatic trypsln inhibitor with sodium borohydride results in the selective cleavage of the disulfide bond linking half-cystine residues 14 and 38.The partially reduced inhibitor is fully active, whereas its carboxymethylated derivative is completely inactive and is susceptible to tryptic digestion.The reduced inhibitor slowly reoxidizes when incubated alone at pH 8.In contrast, when the reduced inhibitor is first allowed to form a complex with trypsin, no reoxidation occurs at pH 8.0 for at least 25 min.