| Abstract: | Parameters were derived for guanosine triphosphate (GTP) and GTP analogs suitable for the AMBER force field. Electrostatically derived net atomic charges and force parameters were extracted from MNDO semiempirical calculations. The later parameters came from fitting MNDO and AMBER atom–atom forces in a manner that is extensible to other compounds that lack sufficient vibrational spectral data. The geometric parameters for these compounds were obtained from model compounds in the Cambridge crystallographic data base. Dynamic simulations of Na4 GTP and Na2 Mg GTP of 140 and 100 ps, respectively, indicated a strong preference for a syn C2′ exo conformation in solution. © 1993 John Wiley & Sons, Inc. |
