Polypeptides with a known repeating sequence of amino-acids. Synthesis of poly-(α- and γ-L-glutamyl-L-alanylglycine)

Abstract

The preparation of two polypeptides with a known repeating sequence of amino-acids by the use of active pentachlorophenyl esters is described. Selective hydrogenolytic removal of the N-benzyloxycarbonyl protecting group under acidic conditions from N-benzyloxycarbonyl-γ-t-butyl and -α-t-butyl-L-glutamyl-L-alanylglycine pentachlorophenyl esters (III and IX) give γ-t-butyl and α-t-butyl-L-glutamyl-L-alanylglycine pentachlorophenyl ester hydrochlorides (IV and X). These active esters were polymerised on preformed monomers at a relatively high dilution to give optically pure poly-(α- and γ-L-glutamyl-L-alanylglycine)(VI and XII). These polymers had weight average molecular weights of 10,000 and 13,500 and number average molecular weights of 6700 and 8000. Optical rotatory dispersion studies at physiological pH indicate a random structure for both polymers.