Tachykinins (Substance P, Neurokinin A and Neuropeptide γ) and Neurotensin from the Intestine of the Burmese Python, Python molurus

Abstract

Conlon, J. M., T. E. Adrian and S. M. Secor. Tachykinins (substance P, neurokinin A and neuropeptide γ,) and neurotensin from the intestine of the burmese python, Python molurus. Peptides 18(10) 1505–1510, 1997.—Peptides with substance P-like immunoreactivity, neurokinin A-like immunoreactivity and neurotensin-like immunoreactivity were isolated in pure form from an extract of the intestine of the Burmese python ( Python molurus). The primary structure of python substance P (Arg-Pro-Arg-Pro-Gln-Gln-Phe-Tyr-Gly-Leu-Met-NH 2) shows one amino acid substitution (Phe 8 → Tyr) compared with chicken/alligator substance P and an additional substitution (Lys 3 → Arg) as compared with mammalian substance P. The neurokinin A-like immunoreactivity was separated into two components. Python neuropeptide γ (Asp-Ala-Gly-Tyr-Ser-Pro-Leu-Ser-His-Lys-Arg-His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met-NH 2 shows three substitutions (Gly 5 → Ser, Gln 6 → Pro and Ile 7 → Leu) compared with alligator neuropeptide γ and an additional substitution (His 4 → Tyr) compared with mammalian neuropeptide γ. Python neurokinin A (His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met.NH 2) is identical to human/chicken/alligator neurokinin A. Python neurotensin (pGlu-Leu-Val-His-Asn-Lys-Ala-Arg-Pro-Tyr-Ile-Leu) is identical to chicken/alligator neurotensin. The data are indicative of differential evolutionary pressure to conserve the amino acid sequences of reptilian gastrointestinal peptides.