Synthesis of the Gastrointestinal Peptide Hormone Secretin by the Repetitive Excess Mixed Anhydride (REMA) Method

The REMA method was found to be very suitable for the synthesis of secretin. The procedure was rapid, since on a 0.2 mmol‐scale the rate of one amino acid per day could be attained, and yielded an unambiguous product after simple ion‐exchange chromatography. REMA‐secretin was found to be chemically identical with secretin prepared by fragment condensations and showed a biological activity of 3.4 (2.9–4.3) clinical units/μg, comparable to that of the natural product (4 clinical units/μg). The yield of purified secretin, a heptacosapeptide amide, calculated on the basis of C‐terminal residue, amounted to 5%.