Characterization Of The S' Subsite Specificity Of Trypsin

The S' subsite specificity of bovine trypsin has been studied by partitioning of o-nitrophenylsulfenyl-L-arginyl-trypsin (formed using o-nitrophenylsulfenyl-L-arginine alkyl esters as acyl donors) between various amino acid-derived nucleophiles and water. The data obtained from spectrophotometric measurements confirmed a preference of trypsin for arginine residues in the P'₁-position, which is less marked but quite similar to that of chymotrypsin. The amides of leucine, phenylalanine, methionine, threonine, lysine and valine are better for synthesis than the corresponding methyl esters, and show a moderate nucleophile efficiency, decreasing in that order. Amides of acidic amino acids and D-leucine were ineffective in forming the peptide bond, whereas norvaline amide and dipeptide amides lead to increased aminolysis.