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Biotechnology and Applied Biochemistry (2001) 33, (183–187) (Printed in Great Britain)

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Studies on peptide amidase-catalysed C-terminal peptide amidation in organic media with respect to its substrate specificity

Václav eovský*^1,2 and Maria-Regina Kula†

*Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo 2, Prague 6, 166 10, Czech Republic, and †Institut für Enzymtechnologie der Universität Düsseldorf, Forschungszentrum Jülich, D-52426 Jülich, Germany

Abbreviations used: DMF, dimethylformamide; Z, benzyloxycarbonyl.

¹ Present address: Department of Chemistry and Chemical Biology, Cornell University, P.O. Box 293, Ithaca, NY 14853-1301, U.S.A.

² To whom correspondence should be addressed, at the Department of Chemistry and Chemical Biology, Cornell University (e-mail vc48@cornell.edu).

Peptide amidase-catalysed amidations of the C- terminal carboxylic group of peptides were studied using model substrates of a large series of N^a-protected di-, tri-, tetra- and penta-peptides in the presence of NH₄HCO₃ as the ammonium source. The maximal yields of amide syntheses were achieved in a medium consisting of acetonitrile with 20–25 vol% of dimethylformamide and 3 vol% of water. Under these conditions, the substrate specificity of the enzyme was more restricted in the synthetic reaction than was found for the amide hydrolysis. Elongation of the peptide chain had a negative effect on enzymic amidation. Thus the direct amidation of N^a-t-butoxycarbonyl-protected Leu-enkephalin resulted in a low yield of protected enkephalin amide.

Received 19 October 2000/15 January 2001; accepted 13 March 2001

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