Nuclear magnetic resonance studies of the solution conformation of nucleoside diphosphohexoses and their components

The solution conformations of UDPG, UDPGN, UDPGal, UDPM, UDPGluc, UDPGalc, ADPG, ADPM, GDPG, GDPM, and CDPG and their components Glu-1-P, Gal-1-P, Man-1-P, Gluc-1-P, Galc-1-P, ADP, GDP, UDP, and CDP are studied by high resolution fast Fourier transform nuclear magnetic resonance spectroscopy with iterative computer line shape simulation. The following results were observed. (1) The six-membered ring is in 4C1 chair form with the C(5')-C(6') bond in gg equilibrium tg equilibrium for the derivatives of glucose and mannose and gt equilibrium tg for those of galactose. (2) No conformational preference can be detected for C(1')-O(1') bond in hexose-1'-P moiety. (3) Chemical shift dependencies for the pyranoid ring protons and their structural and conformational relations are: (a) axial proton is at higher field than equatorial: (b) the shielding effect of a gauche vicinal hydroxyl group is stronger than a trans vicinal; (c) the vicinity of a hydroxyl group located more than three bonds away tends to shift the proton downfield. (4) The conformation of the nucleoside 5'-diphosphate part is [anti, 2E equilibrium 3E, g'g' equilibrium g't', g'g' equilibrium g''/t''], with slight variation of each conformation occuring for individual compounds. (5) No significant interactions are detected between the hexose and nucleoside parts in the nucleoside diphosphohexoses, and the hexose and nucleoside components display the same conformational preference as they become integrated to form nucleoside diphosphohexoses.