CARBOHYDRATE-NUCLEOTIDE INTERACTION - THE EFFECTS OF MONOSACCHARIDE AND DISACCHARIDE ON THE SOLUTION STRUCTURE OF AMP, DAMP, ATP, GMP, DGMP, AND GTP STUDIED BY FTIR DIFFERENCE SPECTROSCOPY

The interactions of D-glucose, D-fructose, D-galactose, and sucrose wi th disodium-adenosine-5'-monophosphate (Na(2)AMP), disodium-2-deoxyade nosine-5'-monophosphate (Na(2)dAMP), disodium-adenosine-5'-triphosphat e (Na(2)H(2)ATP), disodium-guanosine-5'-monophosphate (Na(2)GMP), diso dium-2-deoxyguanosine-5'-monophosphate (Na(2)dGMP), and disodium-guano sine-5'-triphosphate (Na(2)H(2)GTP) are investigated in aqueous soluti on at physiological pH with sugar/nucleotide ratios (r) of 1/10, 1/2, 1, and 2. Fourier transform infrared (FTIR) difference spectroscopy is used to establish a correlation between spectral changes and sagar bi nding mode, nucleotide conformation, and sugar anomeric structure, as well as structural properties of sugar-nucleotide complexes in aqueous solution.Spectroscopic evidence showed that at low sugar concentratio n r=1/10, carbohydrate interaction (H-bonding) is mainly through phosp hate (alpha-, beta-, and gamma-PO2- of the triphosphate chain or -PO32 - of monophosphate) groups, while at higher sagar content (r>1/10), su gar interaction (H-bonding) extends to base donor sites (adenine NH2, N-1, and N-7 groups and guanine O-6 and N-7 atoms). The sugar-phosphat e binding is quantitatively larger for the phosphate groups (30-60%+/- 5%) than for the bases donor atoms (10-35%+/-3%). Evidence for sugar-p hosphate interaction (H-bonding) comes from major spectral changes (in tensity alterations and shiftings) of the antisymmetric and symmetric stretching vibrations of the PO32- and different PO2- groups, located at 1250-900 cm(-1), whereas sugar base binding (H-bonding) is characte rized by the spectral alterations (intensity variations and shiftings) of the pyrimidine and imidazol in-plane vibrations at 1700-1400 cm(-1 ). Evidence for sugar complexation also comes from the spectral shifti ngs of the carbohydrate OH stretchings (3500-3200 cm(-1)) and OH bendi ngs (1450-1200 cm(-1)), as well as the C-O and C-C stretching frequenc ies (1100-900 cm(-1)). The ribose and deoxyribose moieties of the free ATP, RMP, and dAMP with C2'-endo/anti conformation (with marker infra rared band at 820-825 cm(-1)) exhibit no alteration upon sugar complex ation. Similarly, the ribose and deoxyribose of guanosine-nucleotides with C2'-endo/anti- and C3'-endo/anti sugar packers with marker IR ban ds at 800-822 cm(-1) show no major conformational alteration on carboh ydrate complexation. The sugar interaction occurs via both alpha- and beta-anomeric structures. (C) 1997 Elsevier Science Inc.