Calcitonin gene related peptides are produced by enzyme-assisted reverse proteolysis. Reaction of a C-terminal truncated calcitonin gene related peptide or a protected derivative with a C-terminal amidated peptide or amino acid, or ammonia in the presence of a hydrolase, yields a calcitonin gene related peptide (CGRP) in good yield and high purity. The CGRP product may be a naturally occurring CGRP or an analogue thereof, such as human alpha - or beta -CGRP. Particular hydrolases include serine proteases such as chymotrypsin, trypsin, thrombin, plasmin, elastase, endoproteinase Lys C; endoproteinase Glu C, or endoproteinase Arg C, acid proteases such as pepsin; metalloproteinases such as thermolysin; and sulphydryl proteinases such as papain or clostripain.
A process for the production of calcitonin gene related peptides.