A Shortened Insulin with Full in vitro Potency

Des[(B26-30)-pentapeptide]insulin-B25-amide was prepared from protected des-[(B23-30)-octapeptide]insulin (pig) and H-Gly-Phe-Phe-NH2 by trypsin-mediated semisynthesis in a yield of 9% (based on insulin). The analogue was characterized with respect to chemistry, biological function and CD spectroscopy. While des[(B26-30)-pentapeptide]insulin with free carboxylate group exhibited a typical insulin activity of only 25% in vitro, des[(B26-30)-pentapeptide]insulinamide was fully active. Therefore des[(B26-30)-pentapeptide]insulin meets all structural and dynamic requirements for recognition and binding of the receptor as well as exertion of the biological effect, provided that the negative charge in the hydrophobic environment of PheB25 is neutralized.