Triphosphate nucleotides

Nucleotide sugars Nucleotide triphosphates NUCLO-ADD Nuctalon NUDAT Nude... 

The deterrnination of the presence of reverse transcriptase in vims-infected cells can be done using labeled nucleotide triphosphates. Reverse transcriptase is an enzyme capable of synthesizing DNA from RNA and it is thought to play an important role in vims-mediated cell modification. This enzyme is also a marker enzyme for HIV, the vims impHcated in causing acquired immunodeficiency syndrome (AIDS). The procedure utilizes radiolabeled nucleotides with nonlabeled substrates to synthesize tagged DNA. The degree of radioactive incorporation reflects the reverse transcriptase activity. 

While metal-nitrogen and metal-oxygen bonded compounds dominate nucleobase coordination chemistry, examples in which metal-carbon bonds are formed have been identified. Early studies on the synthesis of metal-labeled DNA demonstrated that nucleotide-triphosphates, UTP, CTP, dUTP, and dCTP, can undergo mercury modification at C5 (82,83). The UTP derivative was also shown to act as a substrate for RNA polymerase in the presence of mercaptans (83). Later, guano-sine was shown to undergo mercury modification at C8 though, in this case, the purine was multiply substituted, 21 (84). 

Nucleotide triphosphates Mobile carrier of phosphate and energy... 

Both the 26S proteasome and the RC hydrolyze all four nucleotide triphosphates, with ATP and CTP preferred over GTP and UTP [58]. Although ATP hydrolysis is required for conjugate degradation, the two processes are not strictly coupled. Complete inhibition of the peptidase activity of the 26S proteasome by calpain inhibitor I has little effect on the ATPase activity of the enzyme. The nucleotidase activities of the RC and the 26S proteasome closely resemble those of E. coli Lon protease, which is composed of identical subunits that possess both proteolytic and nucleotidase activities in the same polypeptide chain. Like the regulatory complex and 26S proteasome, Lon hydrolyzes all four ribonucleotide triphosphates, but not ADP or AMP [18]. 

The amino group now provides the nucleus for purine ring formation, an extended series of reactions we shall not describe. The first-formed purine product is inosine 5 -phosphate (IMP), which leads to either AMP or GMP these require amination at alternative sites, and utilize either GTP- or ATP-dependent reactions for amination. GTP or ATP (as appropriate) will also be required for further phosphorylations to produce the nucleotide triphosphates. 

Nucleotide Base Conformation. Using NMR data, a relationship between the degree of specificity and the conformation of bound ATP at the active site has been shown for a number of ATP utilizing enzymes. Two examples of these are cAMP-dependent protein kinase and pyruvate kinase (18,19) It appears that enzymes that exhibit higher nucleotide triphosphate specificity bind ATP so... 

Figure 2. a) Glycosidic bond angle(x) in nucleotide triphosphates b) 8-BrATP c) 8,5 -Cyclo-AMP d) Adenylyl imidodi-phosphate e) 8,y-Adenylyl methylene bisphospho-... 

DNA template and the enzyme T7RNA polymerase microinjected into a selected giant vesicle nucleotide triphosphates added from the external medium... 

The first step of a PCR involves DNA denaturation at 90-95 °C, in a buffered, neutral, aqueous solution containing DNA polymerase, the four deoxynucleotide triphosphates and Mg++, in the presence of a large excess of the two primers (Fig. 27). In the second step, the temperature of the reaction is lowered to about 10 °C below the melting temperature of the primers and the primers (which are considerably smaller than the DNA) are allowed to hybridize to their complementary sequence on the DNA template molecule. This temperature is still too high for the DNA to fully renature. The temperature is then raised to 72 °C, the optimal temperature for extension of the primers by the DNA polymerase, which catalyses the addition of nucleotide triphosphates to extend the sequence in each direction from the... 

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