title: Conformational preference of Leu side chain in melanostatin in DMSO.
abstract: The solution conformation of melanostatin (Pro-Leu-Gly-NH2) in the neutral and protonated forms of DMSO has been monitored by one and two dimensional NMR techniques at 500 MHz. The temperature coefficients of the amide proton chemical shifts in conjunction with the observed NOESY spectra suggest that melanostatin in neutral form in DMSO adopts a backbone conformation such that leucine amide proton is buried by the proline ring and the side chain of leucine. Similar observation is made for protonated form of melanostatin in DMSO. The results of the present study are at variance with the earlier NMR studies which proposed a beta-turn structure for both the forms of melanostatin. There is, however, no evidence for the presence of beta-turn structure for both the forms of melanostatin in DMSO. In CDCl3 also Leu NH appears to be buried as evident from the solvent titration with DMSO and NOESY spectra.
authors.affiliation: Chemical Physics Group, Tata Institute of Fundamental Research, Bombay, India.
authors.forename: Y U
authors.initials: YU
authors.lastname: Sasidhar
authors.forename: M M
authors.initials: MM
authors.lastname: Dhingra
authors.forename: A
authors.initials: A
authors.lastname: Saran
mesh_terms: D004121:Dimethyl Sulfoxide; D009075:MSH Release-Inhibiting Hormone / Q000031:analogs & derivatives* / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D012997:Solvents
chemical_list: D012997:Solvents; C055207:prolyl-leucyl-glycine; D009075:MSH Release-Inhibiting Hormone; D004121:Dimethyl Sulfoxide