title: Study on the influence of tyrosine deprotonation on the myotropic action of angiotensin II.
abstract: The influence of phenolic tyrosine ionization in angiotensin II on the myotropic action of this peptide has been investigated in vitro on rabbit aortic strips. [Sar1, Tyr4]angiotensin II and [Sar1, (4'-amino) Phe4]angiotensin II (as a reference which cannot undergo the same ionization) were tested over a pH range from 6.8 to 9.0 and their activities compared. The results clearly indicate that angiotensin II with a deprotonated phenolic hydroxyl group on Tyr in position 4 is not the most active or only active form of angiotensin II.
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D011817:Rabbits; D013329:Structure-Activity Relationship; D014443:Tyrosine
chemical_list: D000804:Angiotensin II; D014443:Tyrosine