800-73-7Relevant academic research and scientific papers
A unique cysteine-rich zinc finger domain present in a majority of class II ribonucleotide reductases mediates catalytic turnover
Loderer, Christoph,Jonna, Venkateswara Rao,Crona, Mikael,Grinberg, Inna Rozman,Sahlin, Margareta,Hofer, Anders,Lundin, Daniel,Sj?berg, Britt-Marie
, p. 19044 - 19054 (2017)
Ribonucleotide reductases (RNRs) catalyze the reduction of ribonucleotides to the corresponding deoxyribonucleotides, used in DNA synthesis and repair. Two different mechanisms help deliver the required electrons to the RNR active site. Formate can be used as reductant directly in the active site, or glutaredoxins or thioredoxins reduce a C-terminal cysteine pair, which then delivers the electrons to the active site. Here, we characterized a novel cysteine-rich C-terminal domain (CRD), which is present in most class II RNRs found in microbes. The NrdJd-type RNR from the bacterium Stackebrandtia nassauensis was used as a model enzyme. We show that the CRD is involved in both higher oligomeric state formation and electron transfer to the active site. The CRD-dependent formation of high oligomers, such as tetramers and hexamers, was induced by addition of dATP or dGTP, but not of dTTP or dCTP. The electron transfer was mediated by an array of six cysteine residues at the very C-terminal end, which also coordinated a zinc atom. The electron transfer can also occur between subunits, depending on the enzyme's oligomeric state. An investigation of the native reductant of the system revealed no interaction with glutaredoxins or thioredoxins, indicating that this class IIRNRuses a different electron source. Our results indicate that the CRD has a crucial role in catalytic turnover and a potentially new terminal reduction mechanism and suggest that the CRD is important for the activities of many class II RNRs.
Identification of enzymes catalyzing two-step phosphorylation of cidofovir and the effect of cytomegalovirus infection on their activities in host cells
Cihlar, Tomas,Chen, Ming S.
, p. 1502 - 1510 (2007/10/03)
Cidofovir [CDV; (S)-1-(3-hydroxy-2-phosphonomethoxyethyl)-cytosine] is an acyclic nucleotide analog with potent and selective in vitro and in vivo activities against a broad spectrum of herpesviruses and other DNA viruses. We studied the mechanism of enzymatic synthesis of CDV diphosphate, the putative antiviral metabolite of CDV. The phosphorylation is two-step process catalyzed by several enzymes. An enzymatic activity phosphorylating CDV to its monophosphate derivative was purified from human liver and identified as pyrimidine nucleoside monophosphate kinase (EC 2.7.4.14.). CDV (K(m) = 2.10 ± 0.18 mM and V(max) = 1.10 ± 0.05 μmol/min/mg) was found to be a substantially weaker substrate for purified enzyme than CMP, UMP, or dCMP. Pyrimidine nucleoside monophosphate kinase was used for preparative enzymatic synthesis of CDV monophosphate. Pyruvate kinase (EC 2.7.1.40), creatine kinase (EC 2.7.3.2), and nucleoside diphosphate kinase (EC 2.7.4.6) were found to catalyze CDV diphosphate synthesis from CDV monophosphate, whereas phosphoglycerate kinase (EC 2.7.2.3) and succinyl-CoA synthetase (EC 6.2.1.4) did not. Based on V(max)/K(m) (phosphorylation efficiency) values determined with enzymes purified from human sources, the most efficient phosphorylation of CDV monophosphate is catalyzed by pyruvate kinase. After infection of human lung fibroblasts with cytomegalovirus, the intracellular activities of pyrimidine nucleoside monophosphate kinase, pyruvate kinase, creatine kinase, and nucleoside diphosphate kinase increased 2-, 1.3-, 3-, and 5-fold, respectively. The metabolism of [3H]CDV in mock- and cytomegalovirus-infected cells was examined. The intracellular levels of CDV monophosphate and CDV diphosphate increased ~20- and 8-fold, respectively, in cytomegalovirus-infected cells, presumably due to the stimulation of CDV uptake and higher activities of phosphorylating enzymes.
Nucleoside-Triphosphatase Activity of an ATP-Dependent Enzyme, N-Methylhydantoin Amidohydrolase
Ogawa, Jun,Nirdnoy, Warawadee,Yamada, Hideaki,Shimizu, Sakayu
, p. 1737 - 1739 (2007/10/02)
N-Methylhydantoin amidohydrolase, which catalyzes ATP-dependent hydrolysis of N-methylhydantoin to N-carbamoylsarcosine, was found to hydrolyze several nucleoside triphosphates to nucleoside diphosphates not only in the presence but also in the absence of amide substrates.Amide substrates, such as N-methylhydantoin and dihydrouracil, seem to be absolutely necessary for hydrolysis of ATP and dATP.However, N-methylhydantoin inhibited the hydrolysis of nucleoside triphosphates other than ATP and dATP.The kinetic data suggest that the presence of an amide substrate changes the affinity of the enzyme toward nucleoside triphosphates.
Chemical Synthesis of 5'-Phosphorylated DNA Fragments and Their Constituents
Jankowska, Jadwiga,Stawinski, Jacek
, p. 17 - 22 (2007/10/02)
Phosphoryl tris-triazole has been applied to the synthesis of DNA fragments and their constituents bearing 5'-phosphomonoester function and to the preparation of deoxynucleoside 5'- or 3'-diphosphates.
