Racemization in the synthesis of sequential polypeptides using N‐hydroxysuccinimide esters

Racemization in the synthesis of peptide intermediates and their polymers was investigated, using L‐amino acid oxidase. The formation of N‐hydroxysuccinimide esters from N‐protected peptide acids yielded optically pure products in contrast to p‐nitrophenyl and pentachlorophenyl active esters. The racemization in the polymerization step was found to be base sensitive. Partially racemized polymer can result from optically homogeneous monomer. Thus, the optical integrity of active monomer species carries no guarantee for that of the polymer.