The specificity of prolyl endopeptidase from Flavobacterium meningoseptum:: Mapping the S′ subsites by positional scanning via acyl transfer

The S-1'-S-3' subsite specificity of prolyl endopeptidase from Flavobacterium meningoseptum was studied by acyl transfer to libraries of amino acid amides and peptides. Whereas the S-1' and S-3' subsites influence the specificity for the amino component by approximately one order of magnitude, the S-2' subsite possesses a markedly higher specificity. Besides the high specificity for hydrophobic residues at P-1'-P-3', proline was efficiently bound by the S-2' and S-3' subsites of the enzyme. In contrast, no binding of P-1' proline-containing peptides was observed. It could be demonstrated that the specificity of the S' subsite is not restricted to L-amino acids. Effective P'-S' interactions were also found for beta- and gamma-amino acids indicating that the enzyme does not form close contacts to the backbone of P-1' and P-2' amino acid residues. (C) 1998 Elsevier Science Ltd. All rights reserved.