Syntheses of motilin analogues

According to a first suggestion for the primary structure of the gastrointestinal hormone motilin, two analogues containing norleucine and leucine instead of methionine in the sequence position 13 (primarily called 13-norleucine and 13-leucine-motilin) have been synthesized. Both synthetic peptides were biologically active in equivalence to the natural product. A correction of the proposed amino acid sequence became necessary after rechecking the results by comparison with the synthetic materials. The two analogues must therefore correctly be named 13-norleucine-14-desamidomotilin and 13-leucine-14-desamido-motilin.