Synthetische Analoge des Hypertensins. IV. Synthese der kettenhomologen Peptide (des‐Asp1)‐Val5‐Hypertensin II, (des‐Phe8)‐Val5‐Hypertensin II‐Asp1‐β‐amid, (homo‐Tyr4′)‐Val5‐Hypertensin II und (homo‐Tyr4′)‐Val5‐Hypertensin II‐Asp1‐β‐amid

Abstract

The syntheses of the chain‐homologues of hypertensin, H · Arg‐Val‐Tyr‐Val‐His‐Pro‐Phe · OH, H · Asp(NH2)‐Arg‐Val‐Tyr‐Val‐His‐Pro · OH, and H · Asp(R)‐Arg‐Val‐Tyr‐Tyr‐Val‐His‐Pro‐Phe · OH (R  −OH and −NH2), are described in detail. A system for the nomenclature of such analogues is proposed. The relative stability of H · Arg‐Val‐Tyr‐Val‐His‐Pro‐Phe · OH, H · Gly‐Arg‐Val‐Tyr‐Val‐His‐Pro‐Phe · OH2 and H · Asp(R)‐Arg‐Val‐Tyr‐Val‐His‐Pro‐Phe · OH in aqueous solution at 50° over a period of 6 months is discussed: the heptapeptide and Val5‐hypertensin II are very stable under these conditions, but the asparaginyl1‐ and glycyl1‐ compounds lose these residues to an extent of about 10%. A possible mechanism explaining the difference in the behaviour of the aspartyl and the asparaginyl residues is suggested.