title: Analysis of internal motions of RNase T1 complexed with a productive substrate involving 15N NMR relaxation measurements.
abstract: The backbone dynamics of RNase T1 in the presence of exo-guanosine 2',3'-cyclophosphorothioate (exo-cGPS isomer), which is a productive substrate, and in the presence of 3'-guanylic acid (3'GMP), which is an nonproductive substrate, were examined using (15)N nuclear magnetic resonance. Although the X-ray crystal structure suggests that the modes of binding of these substrates to the active-site cleft are very similar, the order parameters in a number of regions in RNase T1 complexed with exo-cGPS isomer were different from those with 3'GMP. Moreover, the chemical exchange in line width observed for RNase T1 complexed with exo-cGPS isomer was also different from that observed for RNase T1 complexed with 3'GMP. From these results, we concluded that the internal motions in RNase T1 complexed with a productive substrate were not always identical to those in RNase T1 complexed with a nonproductive substrate.
authors.affiliation: Department of Immunology, Department of Pharmaceutical Synthetic Chemistry, and NMR Section, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Masakazu
authors.initials: M
authors.lastname: Tanaka
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Ohkuri
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Taiji
authors.initials: T
authors.lastname: Imoto
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ueda
mesh_terms: D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D006157:Guanosine Monophosphate / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D006163:Ribonuclease T1 / Q000737:chemistry / Q000378:metabolism*; D013873:Thionucleotides / Q000378:metabolism*
chemical_list: D009587:Nitrogen Isotopes; D013873:Thionucleotides; C001774:guanosine 2',3'-cyclophosphorothioate; C068152:3'-guanylic acid; D006157:Guanosine Monophosphate; D006163:Ribonuclease T1; D006152:Cyclic GMP