Conformation of nucleosides

Sundaralingam M (1969) Stereochemistry of nucleic acids and their constituents, IV. Allowed and preferred conformations of nucleosides, nucleoside mono, di, tri, tetraphosphates, nucleic acids and polynucleotides. Biopolymers 7 821-830... 

The use of paramagnetic ions to examine the binding sites and solution conformations of nucleosides and nucleotides is becoming very widespread. Studies that describe the complexing of a variety of nucleosides and nucleotides with paramagnetic ions involve the use of Mn(ii), (749-751) Cu(ii), (750, 752-754) and lanthanide ions. (755) Mn " ions appear to bind to multiple sites on purine and pyrimidine nucleosides (749) whereas the phosphate group is the primary binding site on monophosphate nucleotides. (750) relaxation studies indicate that Cu " ions bind to N-3 of 5 -cytidine monophosphate (5 -CMP). In contrast to cytidine [59], adenosine [60] appears to have... 

Similar stereoelectronic effects strongly influence the favored conformations of nucleosidic ribose and deoxyribose derivatives [40]. 

Within the last half decade a number of laboratories have undertaken investigations of the physical and chemical properties of nucleic acid constituents utilizing 1 3C nmr techniques. The main areas of investigation were the structure and conformation of nucleosides and... 

The conformation of nucleosides and nucleotides has been reviewed.The conformation of 2-alkylthio-2, 3 -0-isopropylidene-adenosine derivatives has been studied by i.r. and c.d. measurements a strong hydrogen bond exists between N-i and 0-5 in carbon tetrachloride, indicating a syn conformation for the base c.d. curves, which are markedly dependent on the sulphur substituent, suggest a syn conformation in chloroform and an anti arrangement in water. 

The effect of packing forces and hydrogen bonds upon the observed puckered conformations of nucleosides in the solid state is well-known [56, 57]. [the anomeric effect across the 3 O-P-O-ester fragment in the sugar-phosphate backbone see references cited therein]. Solution and solid-state conformations of pentofuranose differ dramatically for some nucleosides adenosine [58] crystallizes as the N-type conformer, whereas its hydrochloride salt crystallizes as the S-type conformer [59]. 

Glycosldlc bond conformations of nucleosides and nucleotides have been Investigated by V( C,Hl ) measurements (Lemleux, 1973 Schwelzer and Krelshman, 1973 Davies, 1976). It was shown that observation of vicinal coupling constants between H(l ) and both C(2) and C(6) of pyrimidine rings Is necessary to determine either syn- or anti-type conformations unless HI ) > (Davies, 1976). It Is expected... 

There is a tendency to visualize nucleoside and nucleotide structures as they are written on paper, and not as they exist in the aqueous environment of their biological occurrence and function. This chapter therefore reviews very briefly current knowledge of the configuration and conformations of nucleosides and nucleotides, with an emphasis, wherever possible, on their steric form in aqueous solution. The literature through 1968 is listed and discussed in the review of Preobrazhenskaya and Sha-barova (I) see also Jordan (2). 

Extensive reference to the use of n.m.r. spectroscopy in studies of the conformations of nucleosides is made in Chapter 23, and the application of mass spectrometry and of polarimetry to nucleosides is referred to in Chapters 24 and 25, respectively. 

Aspects of the conformations of nucleoside diphosphohexoses e.g. UDP-d-Glc) and their components in aqueous solution have been examined using H n.m.r. measurements. The hexose and nucleoside components were each shown to prefer identical conformations both in free and combined forms. 

S. Dijkstra, J.M. Benevides, G.. Thomas, Jr. Solution Conformation of Nucleoside... 

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