title: Proton nuclear magnetic resonance study of the solution conformation of C3a-Arg69, a 69-residue N-terminal fragment of the third component of complement.
abstract: A proton nuclear magnetic resonance (NMR) study is reported of human C3a-Arg69, which is a 69-residue fragment obtained by the tryptic cleavage of human C3. It has been shown that the combined use of a CPase/digestion difference spectroscopy method (Endo and Arata (1985) Biochemistry 24, 1561-1568) with a variety of two-dimensional NMR techniques is effective in advancing spectral assignments for structural analyses. On the basis of the results of the NMR measurements, we have concluded that: 1) the N-terminal region of the C3a molecule plays a crucial role in stabilizing the conformation of the C-terminal segment Leu63-Arg69 and 2) the existence of the core region, which is formed by segment Tyr15-Tyr59 (Huber et al. (1980) Hoppe Seyler's Z. Physiol. Chem. 361, 1389-1399), is essential in maintaining this conformation. We also suggest that the disorder of the N-terminal region, which is invisible by the X-ray crystallographic study, is due to dimerization of this molecule in the crystal.
authors.affiliation: Faculty of Pharmaceutical Sciences, University of Tokyo.
authors.forename: Y
authors.initials: Y
authors.lastname: Muto
authors.forename: F
authors.initials: F
authors.lastname: Inagaki
authors.forename: Y
authors.initials: Y
authors.lastname: Arata
mesh_terms: D000595:Amino Acid Sequence; D003176:Complement C3 / Q000032:analysis*; D003460:Crystallization; D006801:Humans; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D010447:Peptide Hydrolases; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: D003176:Complement C3; D010447:Peptide Hydrolases