Synthesis of ala-pro-gly-[Ile3, Val5]angiotensin II isolated from the skin of the australian frog Crinia georgiana.

Ala-Pro-Gly-[Ile3, Val5]angiotensin II was synthesized by Merrifield's solid-phase procedure. The peptide was purified by chromatography on successive columns of anion-exchange resin, Sephadex G-25 and SP-Sephadex C-25; its homogeneity was determined by degradation with alpha-chymotrypsin, ionophoresis, thin-layer chromatography, and high-pressure liquid chromatography (HPLC). The dansyl derivative of this angiotensin has the same chromatographic behavior (TLC) as the dansyl undecapeptide, "Crinia angiotensin II", isolated from the skin of the Australian frog Crinia georgiana. The pressor activity of the synthetic undecapeptide (in rats anesthetized with sodium amytal, followed by treatment with a solution of hexamethonium chloride containing polyvinylpyrrolidone, and vagotomy) was 90.6 +/- 4.99% (n = 26, 7 rats) of that of [Ile5]angiotensin II (human angiotensin II).