Ochoa and his collaborators (6) have shown that cell-free extracts of certain bacteria can be used to accomplish the net synthesis of polynucleotides resembling ribonucleic acid (RNA)1 from purine and pyrimidine nucleoside diphosphates. The net synthesis of RNA by cell-free prepara tions from animal tissues has not been reported. However, renewal or turnover of RNA components in preparations fr...

Ecto-nucleoside triphosphate diphosphohydrolases (ecto-NTPDases), also known as ecto-ATPases and/or ectoapyrases, are integral membrane glycoproteins or soluble enzymes that are dependent on divalent cations. These ectoenzymes are important ecto-nucleotidases that are characterized by the ability to hydrolyze nucleoside triphosphates and nucleoside diphosphates to the monophosphate form. The hy...

The population of short DNA molecules (less than 10(3) nucleotides) in 3T3 cells has been studied using in vivo and in vitro pulse labeling techniques and in vitro end-labeling. There is a large number of molecules of less than 100 nucleotides present in equal numbers in both Go and S phase cells. In S phase cells, most of these molecules are not replicating intermediates because they do not be...

The effects of several nucleoside triphosphates as activators and inhibitors of the enzymic reduction of ribonucleoside diphosphates to deoxynucleotides was studied. The enzyme was a partially purified preparation of the ribonucleotide reductase system from the Novikoff ascites rat tumor, with dithioerythritol used as a model reducing agent. The reduction of cytidine diphosphate and uridine dip...

In spite of their complete lack of any structural features that characterize membrane proteins, cytosolic nucleoside-diphosphate kinases (NDPKs) have been found repeatedly to associate with membranes. In some instances the recruitment of cytosolic NDPKs to membranes was attributed to interactions with peripheral or integral membrane proteins, but in many cases the mechanism underlying the assoc...

This reversible reaction has been demonstrated With enzyme preparations from Azotobacter trinelundii (1, 2) and Escherichia coli (3). In the forward direction the enzyme catalyzes the formation of polyribonucleotides similar in structural details to natural RNA1 (5-8). In the reverse reaction polyribonucleotides are phosphorolyzed to yield nucleoside diphosphates. The phosphorolysis of syntheti...

Nucleoside diphosphate kinase (NDK), an enzyme encoded by the Drosophila abnormal wing discs (awd) or human nm23 tumor suppressor genes, generates nucleoside triphosphates from respective diphosphates. We demonstrate that NDK regulates synaptic vesicle internalization at the stage where function of the dynamin GTPase is required. awd mutations lower the temperature at which behavioral paralysis...

The title compound, hepta-sodium tetra-chromium(III) tetra-kis-(diphosphate) orthophosphate, was synthesized by solid-state reaction. Its structure is isotypic with that of Na7 M 4(P2O7)4PO4 (M = In, Al) compounds and is made up from a three-dimensional [(CrP2O7)4PO4](7-) framework with channels running along [001]. The three Na(+) cations are located in the voids of the framework. One of the c...

Hydroxyurea (HU) is an inhibitor of DNA synthesis, which can inhibit the enzyme ribonucleotide reductase, reduce the syntheses of all four deoxyribonucleoside diphosphates (dNDP), and disturb the balance of the dNTP pool. We have studied the effect of HU on the common fragile site at 3p14 (FRA3B) and have found that G2 treatment with HU increased not only the frequency of chromosomal aberration...

Hydrogenosomes of the anaerobic flagellate Tritrichomonas foetus can use oxygen as terminal electron acceptor in pyruvate metabolism. In particles broken with the detergent, Triton X-100 or by repeated freezing and thawing, pyruvate-supported respiration is greatly enhanced by coenzyme A. Additions of small amounts of CoA result in a phenomenon resembling respiratory control. ADP and GDP also h...