Nucleotide esters

The nucleotide esters 46 and 47 are often referred to as D-ribitol 5-pyrophosphate and L-glycerol 3-pyrophosphate derivatives. 

When incubated with the appropriate nucleotide esters of sugars, membranes from several sources2 were effective in catalyzing the formation of Man-P-Dol, Glc-P-Dol, and GlcNAc-PP-Dol (reactions I, 2,... 

The mechanism of inhibition of glycosylation of protein by FMan has not yet been investigated in detail however, the result that residual glycosylation of protein, noted in the presence of FGlc, does not occur in the presence of FMan indicates a different inhibitory mechanism.282 Nucleotide esters of fluoro sugars have not yet been synthesized in sufficient amount to permit testing this idea. 

In eukaryotic cells, amphomycin inhibits the formation of GlcNAc-PP-Dol, Man-P-Dol, and Glc-P-Dol from their respective nucleotide esters of sugars and Dol-P.134,158,347,348 These reactions have in common the fact that they require manganese ions and Dol-P, but high concentrations of neither the ion nor the lipid phosphate were able to overcome these blocks. The transfer of preformed Man-P-Dol347 (and, pos-... 

The AG° values at pH 6.6 for UDP-D-glucose and a-D-glucosyl phosphate are -33.494 kj.mol-1 and -21.771 kj.mol-1, respectively, 3 It is assumed that glycosyl nucleotide esters containing bases and glycosyl groups other than uracil and D-glu-cosyl, respectively, have approximately the same AG° values. 

In all studies thus far made on starch synthetase, the incorporation of D-glucose from a D-glucosyl ester of a nucleotide into an acceptor molecule has been made by using a radioactively labeled D-glucosyl group in the nucleotide ester, and so the results are unambiguous. However, the extent of the incorporation of D-glucose into the acceptor was very low in the early experiments, and the view has been expressed that starch synthetase is not the major pathway for metabolism of starch. This conclusion seems very reasonable starch biosynthesis is probably a multi-pathway process. Of interest in this connection is a comparison that has been made of starch synthetase activity in non-waxy and waxy maize and rice. ... 

Ribonuclease is a specific pyrimidine nucleotide ester diesterase, 42,420,426,43 jiose modo of cleavage is indicated by unbroken lines in (VIII). This results in the formation of p3rriniidine cyclic anhydrides which are hydrolyzed to yield, not an isomeric mixture, but only pyrimi-dine-3 -phosphates. Because of the nature of the specificity of ribonuclease a number of polynucleotide fragments remain after exhaustive digestion. They vary from dinucleotides to polynucleotide chains whose length probably reaches 5 residues. These fragments have terminal pyrimidine nucleotide residues joined at carbon 5. ... 

Disconnection from the solid support (ROH = sugar of nucleotide) ester hydrolysis... 

P 815 Y cells by N, O -dibul3rryl cyclic AMP. The in vivo growth of two hormone-dependent mammary tumors was also arrested by Ihls cyclic nucleotide ester, and when administered, in vivo, together with aminophylline, cyclic AMP decreased the growth of Ehrlich carcinoma significantly The apparent ability of cyclic AMP to suppress tumorigenicity was demonstrated with human cancer cells (KB) which, after growth in a medium containli this cyclic nucleotide, lost the ability to form solid tumors in hamster cheek pouches. ... 

Ribonuclease (RNase) catalyzes the hydrolysis of 3, 5 -phosphodiester linkages of ribonucleic acids or nucleotide esters at the 5 -ester bond. 

Phosphodiesterases catalyze the conversion of prochiral substrates to proprochiral products, and several of these enzymes have been investigated in our laboratory wiUi oxygen chiral technology. The substrates for our stereochemical studies have been chiral 0, 0-labeled nucleotide esters, which were prepared according to the procedures described in Section 11,B,1. 

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