Isoleucine-5-angiotensin

The synthesis of the octapeptide isoleucine-5-angiotensin Z-Asp(NH2)-Arg(N02)-Val-Tyr-Ile-His-Pro-Phe-OCH3 using CDI as condensing agent was achieved by preparing the four required dipeptides (1—2), (3-4), (5-6), (7-8), two tetrapeptides (1-4) and (5-8), and finally the octapeptide itself. 123... 

Arakawa K, Bumpus FM. An improved synthesis of isoleucine angiotensin octapeptide. J. Am. Chem. Soc. 1961 83 728-732. Bumpus FM, Schwarz H, Page IH. Synthesis and pharmacology of the octapeptide angiotonin. Science 1957 125 886-887. Marshall GR, Merrifield RB. Synthesis of angiotensins by the solid-phase method. Biochemistry. 1965 4 2394-2401. 

H. Schwarz, M. Bumpus, I.H. Page, Synthesis of a biologically active octapeptide similar to natural isoleucine angiotensin octapeptide. J. Amer. Chem. Soc. 79 5697-5703 (1957)... 

The sequences shown are those of porcine and human angiotensins in the bovine peptide position 5 is occupied by valine rather than isoleucine. Treatment of the intact plasma protein, which is the source of the angiotensins, with trypsin yields a 14-peptide, angiotensinogen, itself a good substrate for renin [2] ... 

Position 5. Natural angiotensins differ in this position. It is occupied by isoleucine in equine and porcine and by valine in bovine angiotensin. 

---