A globular protein with slower amide proton exchange from an alpha helix than from antiparallel beta sheets.
In proteinase inhibitor IIA from bull seminal plasma, which is a small globular protein with 57 amino acid residues, measurements of individual amide proton exchange rates by two-dimensional correlated 1H NMR spectroscopy (COSY) showed that the exchange was slowest for some hydrogen bonded amide groups in an alpha-helix. This contrasts with all other proteins which were so far studied in detail, where the slowest exchange rates were observed for hydrogen bonded amide protons in antiparallel beta-sheets.
D000818:Animals; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D006860:Hydrogen Bonding; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D011480:Protease Inhibitors; D011487:Protein Conformation; D012661:Semen
D011480:Protease Inhibitors