title: High resolution 1H-NMR studies of Des-(B26-B30)-insulin; assignment of resonances and properties of aromatic residues.
abstract: The assignments of 1H resonances of the eight aromatic residues of Des-(B26-B30)-insulin are reported, based on pH titration, selective spin decoupling and its 500 MHz 1H two-dimensional (2D)-COSY spectrum. The pK values of the three tyrosines A14, A19 and B16 are 10.84, 11.27 and 10.40, respectively. Tyrosine A19 is buried in a hydrophobic environment, while Tyrosine B16 is exposed in a relatively hydrophilic state. Among the three phenylalanines, the ring proton resonances of Phe-B25 undergo abnormal upfield shifts, probably due to the ring currents of the nearby Phe-B24 and Tyr-B16. From this study of the low-field region of 1H-NMR spectrum of Des-(B26-B30)-insulin, we conclude that this molecule probably maintains the major structural features of insulin in aqueous solution, but there are some readjustments of the peptide conformation.
authors.affiliation: Institute of Biophysics, Academia Sinica, Beijing, Peoples Republic of China.
authors.forename: Q X
authors.initials: QX
authors.lastname: Hua
authors.forename: Y J
authors.initials: YJ
authors.lastname: Chen
authors.forename: C C
authors.initials: CC
authors.lastname: Wang
authors.forename: D C
authors.initials: DC
authors.lastname: Wang
authors.forename: G C
authors.initials: GC
authors.lastname: Roberts
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000031:analogs & derivatives*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010649:Phenylalanine; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013552:Swine; D014443:Tyrosine
chemical_list: D007328:Insulin; D014443:Tyrosine; D010649:Phenylalanine