Nucleoside sugar

The FAB source operates near room temperature, and ions of the substance of interest are lifted out from the matrix by a momentum-transfer process that deposits little excess of vibrational and rotational energy in the resulting quasi-molecular ion. Thus, a further advantage of FAB/LSIMS over many other methods of ionization lies in its gentle or mild treatment of thermally labile substances such as peptides, proteins, nucleosides, sugars, and so on, which can be ionized without degrading their. structures. 

E xides and oxetanes react readily with lithiodithiane to give derivatives of 3- or y-hydroxy aldehydes or ketones. The method has been used for the multistep synthesis of an inomycin fragment, thietane prostaglandin analogs, branched-chain nucleoside sugars, the southern hexahydrobenzctfu-ran unit avermectin, the anti-Gram-positive bacterial elaiphylin andsyn-l,3-polyols. ... 

In the case of furanosides, especially nucleosides, Altona and Sundara-lingam s original symbols for the pseudorotational angle P and pucker (or sometimes (p are used P = is defined as the T2 conformation. Figure 2.4 shows the pseudorotational itinerary, with a nucleoside (sugar D-ribose) as an example. Nucleoside chemists refer to conformations with 0 < P < 36° as N ... 

Both DNA and RNA are polymers of nucleotides (phosphate-sugar-base), which are formed from nucleosides (sugar-base) and phosphoric acid. However, the polymer chain of DNA is much larger than that of RNA. 

Both chemical and enzymatic syntheses have been reported of nucleoside sugar phosphates.88 An enzymatic synthesis of UDP-d-G1cNAc is shown next 95... 

Sugars, nucleosides and their analogs are the classes of compounds most often involved in enzyme catalyzed phosphorylation. Typical carbohydrate phosphorylations are included in Table 13-4, together with the phosphorylation of other non-nucleosidic compounds. Table 13-5 gives an overview of the enzyme catalyzed phosphorylation reactions of nucleosides and their analogs. A few representative examples of nucleoside sugars are listed, for more detailed information consult the review, refs[74> 80, 81]. 

Alkyl selenides are reduced by (TMS)3SiH, as expected, in view of the affinity of silyl radicals for selenium-containing substrates [54], Equation (20) shows the phe-nylseleno removal from the 2 -position of a nucleoside sugar moiety [53]. 

SLC35 Nucleoside-sugar transporter 17 Leukocyte adhesion deficiency type II... 

At carbon electrodes, purine bases produce well-defined oxidation peaks within a wide pH range (0-12.5) [142,143]. Purine nucleosides and nucleotides are oxidized at potentials more positive than the parent bases [144]. Signals corresponding to the oxidation of purine bases, nucleotides, and nucleotides have also been obtained using chemically modified carbon electrodes [145,146] (for more details see Sect. 12.4.3). Recently, Cai and coworkers [147] proposed a method for trace A determination using an electrochemically/chemically modified (in alkahne sodium nitrate solution) carbon paste electrode (CPE). Pyrimidines are considered to be electroinactive on carbon electrodes however, Oliveira-Brett and Matysik recently reported [148] specific anodic peaks observed in solutions of T and C bases (but not their nucleosides). Sugar components of nucleotides can be oxidized at copper electrodes [149]. 

Several carbohydrate applications have been included in a review of micro-wave-assisted organic reactions, and a survey of chemical reagents in photo-aflinity labelling included the role of various base-labelled azido- and thio-nucleosides, sugar azide derivatives and p-benzoylbenzoate esters of nucleosides. A further review intitled Reverse Anomeric Effect Fact or Fiction refers to early evidence based on studies of glycosyl pyridinium and imidazolium salts. It concludes that its origin as an electronic effect is not supported by theory or experimental results. ... 

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