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The specificity of the S1′ subsite of papain

1974; Portland Press; Volume: 141; Issue: 2 Linguagem: Inglês

10.1042/bj1410495

1470-8728

M. Robert Alecio, Malcolm L. Dann, Gordon Lowe,

Chemical Synthesis and Analysis

The specificity of the S1′ subsite of the proteolytic enzyme papain was investigated by studying the effect of l-α-amino acid amides on the enzyme-catalysed hydrolysis of N-benzyloxycarbonylglycine p-nitrophenyl ester and by determining the kinetic parameters for the enzyme-catalysed hydrolysis of some N-benzyloxycarbonylglycyl-l-amino acid amides. These studies showed that the S1′ subsite has a predilection for hydrophobic residues, in particular l-leucine and l-tryptophan. The specificity for these residues is manifest in both the binding and acylation steps. N-Benzyloxycarbonylglycine amide is not hydrolysed under comparable conditions, indicating that the amide group adjacent to and on the C-terminal side of the peptide bond about to be cleaved makes an important contribution to the rate of the papain-catalysed hydrolysis of peptides.