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Results for “Nucleoside-Diphosphate Kinase”

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At least 19 recordsLinked to original sources
PubMedDate not supplied

P1, P5-Bis-(5'-adenosyl)pentaphosphate: is this adenylate kinase inhibitor substrate for mitochondrial processes?

1. P1, P5-Bis-(5'-adenosyl) pentaphosphate (AP5-A) inhibits "soluble" adenylate kinase even when this enzyme is an integral part of the complete mitochondrion. The Ki is 10(-5) M, i.e. about two orders of magnitude higher than the inhibitor contants determined for the purified adenylate kinase of rabbit muscle and an enzyme preparation separated from the mitochondrial intermembrane space. The weaker inhibitory effect is due to a lower accessibility of the enzyme. 2. as to be expected Ap5A which is of the "multisubstrate analogue"-type does not affect mitochondrial nucleoside diphosphate kinase. 3. Though Ap5A owns the structural elements of both ATP and ADP it is not a substrate of the adenine nucleotide carrier, i.e. neither it is exchanged across the inner mitochondrial membrane nor speicifically bound. 4. Ap5A is not metabolized by rat liver mitochondria.

Adenine Nucleotides↗
PubMed1976

[Effect of alkylating chemical substances on the activity and molecular heterogeneity of mouse sarcoma 180 nucleoside phosphate kinases].

The fractionation of extracts from sarcoma 180 cells was carried out on DEAE-cellulose following the administration to tumor-bearing mice of one of chloroctyl amino-phenildioxan derivatives. The tumor regression was noted more than in 50 per cent. It was found that the tumor regression, caused by this alkylating agent, results in marked changes in the fractionation pattern of thymidilatkinases. The origin of these changes is being discussed.

Alkylating Agents↗
PubMed1977

Enzyme associations in T4 phage DNA precursor synthesis.

A DIRECT APPROACH IS DESCRIBED TO THE QUESTION: Are enzymes of DNA precursor synthesis organized into a supramolecular structure? This approach involved sedimentation analysis of several T4 phage-coded early enzyme activities in crude lysates of infected Escherichia coli. One-third to one-half of several activities tested-dCMP hydroxymethylase, dTMP synthetase, deoxynucleoside 5'-monophosphate kinase, deoxyuridine triphosphatase, and probably dCMP deaminase, but not dihydrofolate reductase or DNA polymerase-sedimented much more rapidly than expected from molecular weight. About 5% of the host cell nucleoside diphosphate kinase, known to participate in T4 DNA precursor synthesis, cosedimented with these activities. To show that this rapidly sedimenting material represents an organized enzyme complex rather than a nonspecific aggregate, we studied the kinetics of formation of dTTP with dUMP as the initial substrate. This three-step reaction sequence reached its maximal rate within a few seconds when catalyzed by enzymes in the aggregate, whereas an equivalent mixture of uncomplexed enzymes required nearly 20 min before dTTP synthesis reached its maximal rate. The effect of aggregation is evidently to decrease the volume into which intermediates are free to diffuse. Because there is reason to believe that intracellular concentration gradients of DNA precursors exist, the properties of this enzyme aggregate in vitro may help to explain how such gradients are maintained.

Coliphages↗
PubMed1977

Synthesis of ribonucleotides and their participation in ribonucleic acid synthesis by Coxiella burnetii.

Synthesis of ribonucleic acid (RNA) by the deoxyribonucleic acid-dependent RNA polymerase of Coxiella burnetii required adenosine, uridine, guanosine, and cytidine 5'-triphosphates. Cell-free preparations of this obligate intracellular procaryotic parasite had competence to phosphorylate ribonucleoside mono- and diphosphates in the presence of exogenous adenosine and guanosine 5'-triphosphates to the corresponding di- and triphosphates. C. burnetii contained about 2 nmol of adenosine 5'-triphosphate per mg of protein, which could serve as a approximately P donor for in vivo synthesis of nucleoside triphosphates. The latter were then used as substrates in the synthesis of RNA in a coordinated metabolic system with C. burnetii RNA polymerase. It is suggested that during infection the rickettsiae might obtain the nucleotides necessary for RNA synthesis from the vacuoles in which C. burnetii proliferates.

Adenosine Triphosphate↗