Angiotensin ii is a vasoconstrictor and an octapeptide. complete acid hydrolysis of the peptide gives the following amino acid composition: arg, asp, his, ile, phe, pro, tyr, val. treatment with phenylisothiocyanate yields an aspartate-phenylisothiocyante derivative. carboxypeptidase treatment releases a phe. trypsin produces a dipeptide and a hexapeptide. chymotrypsin produces two tetrapeptides. edman degradation of one tetrapeptide produces the sequence ile-his-pro-phe. what is the sequence of angiotension ii?