Application of Immobilized Carboxypeptidase Y for Deblocking in Peptide Synthesis
CPY is a metal-free carboxypeptidase from yeast with broad specificity (1). In addition to exopeptidase activity at acid pH, the enzyme is an effective esterase at alkaline pH (1) N -α-Acetyl-L-tyrosine ethyl ester is hydrolyzed faster by CPY than by chymotrypsin. Using immobilized CPY (I-CPY) N-blocked L-amino acid or peptide ethyl esters can be deblocked at the C-terminus without any side reactions as shown in Table 1. Further, as indicated by the results in Table 1, a D-amino acid at the C-terminus prevents ester hydrolysis by I-CPY. This assures optical purity of the final product. Side reactions, deamination of Asn or Gin containing peptides and side chain deprotection of Asp and Glu containing peptides, often encountered by base catalzyed hydrolysis are avoided by using I-CPY for deblocking (2). A racemic mixture of Z-Phe-D, L-Ala-OEt is well resolved and selective removal of α-methyl group from α, β-dimethyl aspartate is readily accomplished with the use of I-CPY.
KeywordsEthyl Ester Peptide Synthesis Racemic Mixture Acid Ethyl Ester Chain Elongation
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- 1.Hayashi, R. in “Methds Enzymol.”, Vol. 45 (L. Lorand, ed.) Academic Press, New York, 1976, p. 568.Google Scholar
- 2.Hirschmann, R. & Veber, D.F., in “The Chemistry of Polypeptides,” (P. G. Katsoyannis, ed.) Plenum Press, New York, 1973, p. 126.Google Scholar
- 3.Gross, E. in “Methods Enzymol.”, Vol. 11 (C. H. W. Hirs, ed.) Academic Press, New York, 1967, p. 238.Google Scholar