title: Synthesis and pharmacological properties of TOAC-labeled angiotensin and bradykinin analogs.
abstract: Angiotensin II (AngII) and bradykinin (BK) derivatives containing the TOAC (2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid) spin label were synthesized by solid phase methodology. Ammonium hydroxide (pH 10, 50 degrees C, l h) was the best means for reverting nitroxide protonation occurring during peptide cleavage. EPR spectra yielded rotational correlation times for internally labeled analogs that were nearly twice as large as those of N-terminally labeled analogs. Except for TOAC(1)-AngII and TOAC(0)-BK, which showed high intrinsic activities, other derivatives were inactive in smooth muscle preparations. These active paramagnetic analogs may be useful for conformational studies in solution and in the presence of model and biological membranes.
authors.affiliation: Department of Biophysics, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062, SP, São Paulo, Brazil.
authors.forename: C R
authors.initials: CR
authors.lastname: Nakaie
authors.forename: E G
authors.initials: EG
authors.lastname: Silva
authors.forename: E M
authors.initials: EM
authors.lastname: Cilli
authors.forename: R
authors.initials: R
authors.lastname: Marchetto
authors.forename: S
authors.initials: S
authors.lastname: Schreier
authors.forename: T B
authors.initials: TB
authors.lastname: Paiva
authors.forename: A C M
authors.initials: AC
authors.lastname: Paiva
mesh_terms: D064753:Ammonium Hydroxide; D000809:Angiotensins / Q000737:chemistry*; D000818:Animals; D001011:Aorta / Q000378:metabolism; D001681:Biological Assay; D001920:Bradykinin / Q000031:analogs & derivatives / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D006168:Guinea Pigs; D006878:Hydroxides / Q000494:pharmacology; D007082:Ileum / Q000378:metabolism; D008297:Male; D009130:Muscle, Smooth / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000737:chemistry*; D010452:Peptide Biosynthesis; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D011817:Rabbits; D051381:Rats; D013113:Spin Labels; D013997:Time Factors; D014599:Uterus / Q000378:metabolism
chemical_list: D000809:Angiotensins; D003497:Cyclic N-Oxides; D006878:Hydroxides; D010455:Peptides; D013113:Spin Labels; D009569:Nitric Oxide; D064753:Ammonium Hydroxide; D001920:Bradykinin; C037109:2,2,6,6-tetramethylpiperidine-N-oxide-4-amino-4-carboxylic acid