Deoxycytidylate deaminase, catalyzing the conversion of dCMP to dUMP, is an important enzyme in the de novo synthesis of thymidine nucleotides. It also may be involved in the action, as well as the metabolism of anticancer agents. Recently, several L- and D-configuration pyrimidine deoxynucleoside analogs were found to be potent antiviral and antitumor agents. Their interaction with dCMP deamin...

The level of intermediates of the photosynthetic carbon cycle was measured in intact spinach chloroplasts in an attempt to determine the cause of the induction lag in CO(2) assimilation. In addition, transient changes in the level of the intermediates were determined as affected by a light-dark period and by the addition of an excess amount of bicarbonate during a period of steady photosynthesi...

The virulence plasmid-carried apy (phoN2) gene of Shigella and related enteroinvasive Escherichia coli (EIEC) encodes apyrase, an ATP-diphosphohydrolase belonging to class A of the non-specific acid phosphatases (A-NSAPs). Apyrase and A-NSAPs share three domains of conserved amino acids (domains D1-D3) containing residues forming the putative active site of apyrase. In spite of their similarity...

A classification system is presented to distinguish 3 corn nucleases-Ribonuclease I, Ribonuclease II, and Nuclease I-which were described in the first paper of this series. The 2 ribonucleases are specific for RNA, are endonucleases, and liberate purine and pyrimidine cyclic nucleotides from dinucleotide monophosphates as well as from RNA. Ribonuclease I and II hydrolyze the purine cyclic nucle...

2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) is an enzyme highly abundant in the central nervous system myelin of terrestrial vertebrates. The catalytic domain of CNPase belongs to the 2H phosphoesterase superfamily and catalyzes the hydrolysis of nucleoside 2',3'-cyclic monophosphates to nucleoside 2'-monophosphates. The detailed reaction mechanism and the essential catalytic amino ac...

Cyclic nucleotide levels are controlled through their synthesis from nucleotide triphosphates by cyclases and their degradation to 5'-monophosphates by phosphodiesterases (PDEs). Components controlling cyclic AMP-induced relaxation in the urinary tract include receptors, inhibitory and stimulatory G-proteins, isoforms of adenylyl cyclase and PDEs. The responsiveness of PDEs to a variety of phys...

The nucleotide pyrophosphatases/phosphodiesterases NPP1 and NPP2/autotaxin are structurally related eukaryotic ecto-enzymes, but display a very different substrate specificity. NPP1 releases nucleoside 5'-monophosphates from various nucleotides, whereas NPP2 mainly functions as a lysophospholipase D. We have used a domain-swapping approach to map substrate-specifying determinants of NPP1 and NP...

of Drosophila melanogaster Meig. is stimulated by the 3′,5′monophosphates of adenosine (cAMP; Dow et al., 1994), guanosine (cGMP; Davies et al., 1995), inosine (cIMP), cytidine (cCMP), thymidine (cTMP) and uridine (cUMP) (Riegel et al., 1998). The way in which these compounds influence fluid secretion is not known, but stimulation may follow from the accumulation of cyclic nucleotides within th...