Tachykinins (substance P, neurokinin A and neuropeptide γ) and neurotensin from the intestine of the Burmese python']python, Python']Python molurus

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 NH2) 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 gamma (Asp-Ala-Gly-Tyr-Ser-Pro-Leu-Ser-His-Lys-Arg-His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met-NH2 shows three substitutions (Gly(5) --> Ser, Gln(6) --> Pro and Ile(7) --> Leu) compared with alligator neuropeptide gamma and an additional substitution (His(4) --> Tyr) compared with mammalian neuropeptide gamma. Python neurokinin A (His-Lys-Thr-Asp-Ser Phe-Val-Gly-Leu-Met.NH2) 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. (C) 1997 Elsevier Science Inc.