Rh. Osborne et al., PROCTOLIN AND RELATED N-METHYLATED PENTAPEPTIDES SELECTIVELY CONTRACTLOCUST FOREGUT BUT NOT RAT ILEUM, Bioorganic & medicinal chemistry letters, 5(18), 1995, pp. 2085-2088
Proctolin contracts locust, but contrary to a previous report, not rat
gut tissue, in a dose-dependent manner. [N-Me-Thr]- and [N-Me-Leu]-,
but not [N-Me-Tyr]-proctolin were also agonists on locust foregut. We
propose that proctolin contains a trans-Pro and exists in a cyclic con
formation based upon solution NMR studies.