AN IMPROVED FERMENTATION PROCESS FOR PRODUCING HIGH LEVELS OF RECOMBINANT HUMAN PROINSULIN IN METHYLOTROPHIC YEAST

摘要

wherein Rl represents a carboxy-protecting group viz., substituted methyl group, which can be deprotected easily, such as t-bUtyl group, diphenylmethyl, 4- methoxybenzyl, 2-methoxybenzyl, 2-chlorobenzyl or benzyl group; R2 represents hydrogen, (C1-C4)alkyl, substituted or unsubstituted phenyl or substituted or unsubstituted phenoxy group. 11 .The chloromethylcephem derivatives of the formula (I) prepared according to the process of the present invention are useful for the preparation of cephalosporin antibiotics of the -