title: Solution conformation of an antibacterial peptide, sarcotoxin IA, as determined by 1H-NMR.
abstract: The solution conformation of sarcotoxin IA, which is an antibacterial peptide isolated from Sarcophaga peregrina with a molecular mass of 4 kDa, was determined by NMR spectroscopy and hybrid distance geometry/dynamical simulated annealing calculations. On the basis of 227 experimental constraints, including 185 distance constraints obtained from NOE and 42 constraints associated with 21 hydrogen bonds, a total of 18 converged structures of sarcotoxin IA were obtained. The final 18 converged structures exhibit backbone-atomic root-mean-square differences about the averaged coordinate positions of 0.070 +/- 0.027 nm for residues 3-23 and 0.040 +/- 0.017 nm for residues 28-38. It has been indicated that sarcotoxin IA consists of two amphiphilic alpha-helical regions, i.e. helix I (Leu3-Gln23) and helix II (Ala28-Ala38), with a hinge region (Gly24-Ile27), which connects helix I and helix II. We conclude that these two amphiphilic helical segments of sarcotoxin IA are of importance for the expression of the antibacterial activity.
authors.affiliation: Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Iwai
authors.forename: Y
authors.initials: Y
authors.lastname: Nakajima
authors.forename: S
authors.initials: S
authors.lastname: Natori
authors.forename: Y
authors.initials: Y
authors.lastname: Arata
authors.forename: I
authors.initials: I
authors.lastname: Shimada
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry*; D002942:Circular Dichroism; D004175:Diptera / Q000378:metabolism; D006860:Hydrogen Bonding; D007301:Insect Hormones / Q000737:chemistry*; D019476:Insect Proteins; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012997:Solvents
chemical_list: D000890:Anti-Infective Agents; D007301:Insect Hormones; D019476:Insect Proteins; D012997:Solvents; C054733:sarcotoxin IA protein, Sarcophaga peregrina