title: The kinetics of the hydrogen/deuterium exchange of epidermal growth factor receptor ligands.
abstract: Five highly homologous epidermal growth factor receptor ligands were studied by mass spectral analysis, hydrogen/deuterium (H/D) exchange via attenuated total reflectance Fourier transform-infrared spectroscopy, and two-dimensional correlation analysis. These studies were performed to determine the order of events during the exchange process, the extent of H/D exchange, and associated kinetics of exchange for a comparative analysis of these ligands. Furthermore, the secondary structure composition of amphiregulin (AR) and heparin-binding-epidermal growth factor (HB-EGF) was determined. All ligands were found to have similar contributions of 3(10)-helix and random coil with varying contributions of beta-sheets and beta-turns. The extent of exchange was 40%, 65%, 55%, 65%, and 98% for EGF, transforming growth factor-alpha (TGF-alpha), AR, HB-EGF, and epiregulin (ER), respectively. The rate constants were determined and classified as fast, intermediate, and slow: for EGF the 0.20 min(-1) (Tyr), 0.09 min(-1) (Arg, beta-turns), and 1.88 x 10(-3) min(-1) (beta-sheets and 3(10)-helix); and for TGF-alpha 0.91 min(-1) (Tyr), 0.27 min(-1) (Arg, beta-turns), and 1.41 x 10(-4) min(-1) (beta-sheets). The time constants for AR 0.47 min(-1) (Tyr), 0.04 min(-1) (Arg), and 1.00 x 10(-4) min(-1) (buried 3(10)-helix, beta-turns, and beta-sheets); for HB-EGF 0.89 min(-1) (Tyr), 0.14 min(-1) (Arg and 3(10)-helix), and 1.00 x 10(-3) min(-1) (buried 3(10)-helix, beta-sheets, and beta-turns); and for epiregulin 0.16 min(-1) (Tyr), 0.03 min(-1) (Arg), and 1.00 x 10(-4) min(-1) (3(10)-helix and beta-sheets). These results provide essential information toward understanding secondary structure, H/D exchange kinetics, and solvation of these epidermal growth factor receptor ligands in their unbound state.
authors.affiliation: Center for Protein Structure Function and Dynamics, University of Puerto Rico, Mayagüez Campus, Mayagüez, Puerto Rico.
authors.forename: Ibon
authors.initials: I
authors.lastname: Iloro
authors.forename: Daniel
authors.initials: D
authors.lastname: Narváez
authors.forename: Nancy
authors.initials: N
authors.lastname: Guillén
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Camacho
authors.forename: Lalisse
authors.initials: L
authors.lastname: Guillén
authors.forename: Elsa
authors.initials: E
authors.lastname: Cora
authors.forename: Belinda
authors.initials: B
authors.lastname: Pastrana-Ríos
mesh_terms: D003198:Computer Simulation; D041961:Deuterium Exchange Measurement / Q000379:methods*; D066246:ErbB Receptors / Q000737:chemistry* / Q000648:ultrastructure*; D007700:Kinetics; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D011487:Protein Conformation
chemical_list: D008024:Ligands; D066246:ErbB Receptors