EXTENDED NATIVE CHEMICAL LIGATION OF THREE OR MORE PEPTIDE FRAGMENTS

摘要

The invention provides a method of assembling oligopeptide intermediates in an extended native chemical ligation reaction that eliminates self-ligation of bi-functional intermediates. An important aspect of the invention is a bi-functional intermediate with an N-terminal heterocyclic protecting group which effectively prevents self-ligation in the chemical assembly process.The N-terminal heterocyclic protecting group of the intermediate is reacted with a nucleophilic agent under acidic conditions to form a N-terminal reactive peptide fragment with a free N-terminal cysteine or a secondary N-terminal amine having the auxiliary group -D-SH, wherein D is a linking moiety. The present invention is useful in methods for convergent synthesis of polypeptides and proteins and improves the efficiency of native chemical ligation reactions, particularly where three or more peptide fragments are used to assemble a polypeptide or protein product and intermediates with no N-terminal cysteine are involved.