Pancreatic juice contains many similar protease enzymes, yet each cleaves only next to particular amino acids. What best accounts for this selectivity?

Core Concept

Specificity arises before chemistry begins. A substrate must dock into a pocket whose size, charge pattern, and hydrophobic character match its target side chain, and induced fit then clamps the complex into a catalytically productive alignment. Neighboring sequences lacking the right features bind weakly and pass through untouched. Random encounter rates and enzyme abundance cannot explain sharp discrimination among chemically similar peptide bonds.