Nucleotide thiophosphate

Nucleotide thiophosphate analogues. The preparation and purification of [ H]ATPyS, [ HJGTPyS, s ITPyS (6-thioinosine), cl ITPyS (6-chloroinosine) and [ HJATPyS are described and the general purification... 

Nucleotide thiophosphate analogues. The preparation and purification of [ HJATPyS, pHJGTPyS, s ITPyS (6-thioinosine), cl ITPyS (6-chloroinosine) and [ HJATPyS are described and the general purification was achieved by chromatography of the nucleotide thiophosphates in the minimum volume of H2O placed onto a DEAE-Sephadex A25 column and eluting with a linear gradient of triethylammonium bicarbonate (0.1 to 0.6M for G and I nucleotides and 0.2 to 0.5M for A nucleotides). [Biochim Biophys Acta 276 155 7972]. 

An additional method to determine the nature of the metal-nucleotide complex that is preferred by the enzyme is in the study of the effects of cation substitution on the stereoselectivity of chiral-specific thiophosphate nucleotides. Thiophosphate derivatives of cAMP, AMP, ADP, and ATP at the a-, /3-, and/or y-positions were initially introduced by Eckstein and co-workers (66, 67) and expanded to several other nucleotides. Substitution of a phosphate oxygen by sulfur at the a-position of cAMP, ADP, or ATP or at the /3-position of ATP gives rise to a new chiral center, Substitution in the a-position of AMP, j8-position of ADP, and the y-position of ATP changes an achiral center to a prochiral center. This substitution gives rise to a small decrease in p a for the phosphate, and with many enzymes these thiophosphate analogs have a decreased substrate ac-... 

Several classes of nucleotide analogue have been used recently (1) thiophosphate derivatives of ATP (2) 170 and 180 derivatives of ATP (3) Crm or Co111 complexes of ATP (4) the fluorescent analogue 2,3-0-(2,4,6-trinitrocyclohexyldienylidine)adenosine diphosphate 152 and (5) photoaffinity analogues.153... 

In the mononucleotide area, the past year has been highlighted by the development of novel phosphate-protecting groups and their use in nucleotide and chiral nucleoside thiophosphate chemistry. Concise methodologies have been described for cost effective syntheses of oligonucleotide building blocks, and the collection of unnatural nucleotides reported to have been synthesised has been considerably expanded. 

DNA contained thiophosphate groups and could be selectively recovered on organomercurial columns. The inorganic thiophosphate must therefore enter the intracellular nucleotide pools, permitting the formation and isolation of thioderivatized DNA without the requirement of adding preformed thiophosphate nucleotides.The cave described previously is, however, still relevant ... 

The conformational barrier for 1,3,2-dioxaphosphorinanes is somewhat greater, although many six-membered phosphates and thiophosphates have been shown to be in equilibrium with twist conformations in solution. The activation energy for chairs twist interconversion of the cyclic nucleotide derivative phenoxy-cTMP [81] has been estimated to be only 2.2kcalmol (this value is proposed as an upper limit) (Nelson et al., 1987). 

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