Solubilisierende Schutzgruppen für enzymatische Peptidsynthesen Untersuchungen mit Polyoxyethylen-gebundenen Substraten

The utility of amino acids and dipeptides esterified to solubilizing polyoxyethylene supports as substrates for protease-mediated peptide bond formation was studied using free and immobilized -chymotrypsin as a catalyst. Poor yields were obtained with N-protected amino acid or dipeptide polyoxyethylene esters as carboxyl components, most probably due to a shielding of the active site of the acyl enzyme intermediate by the polymer favouring hydrolytic cleavage. Experiments with polyoxyethylene esters as nucleophiles gave good results with free chymotrypsin, immobilized chymotrypsin predominantly caused hydrolysis of the ester carboxyl component due to unfavourable interactions between the soluble and insoluble polymers.

Abkürzungen: Die IUPAC/IUB-Regeln für Aminosäure- und Peptidderivate wurden befolgt; vgl. Eur. J. Biochem.53, 1 (1975). Die verwendeten Aminosäuren hattenL-Konfiguration.BOC =tert.-Butyloxycarbonyl,Z = Benzyloxycarbonyl,Ac = Acetyl, –OMe = Methylester, –OPOE = Polyoxyethylenester,POE = -Hydroxy--hydroxypoly(oxyethylen) = Polyoxyethylen,DCC =N,N-Dicyclohexylcarbodiimid,NEM =N-Ethylmorpholin.     

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