Subsite Specificity of Porcine Pepsin

Abstract

The specificity of porcine pepsin toward small synthetic substrates has been extensively investigated (1–4), but only a few papers have dealt with the specificity of this enzyme toward polypeptide or protein substrates. Tang analyzed cleavage sites of 4 proteins by pepsin and concluded that the enzyme possessed a hydrophobic binding site (5). In addition, bonds split by pepsin in seven peptides or proteins of established sequence have been summarized by Hill (6). In neither study was the sample size large enough to yield any information other than the primary specificity of pepsin. Antonov and his coworkers (7) recently reported a more extensive analysis of pepsin specificity toward protein substrates and concluded that the enzyme possessed five subsites.