Adenosine deaminase isoenzymes of the opossum Didelphis virginiana: initial chromatographic and kinetic studies.

Extracts of liver and spleen were used to isolate opossum adenosine deaminase isoenzymes (ADA1 and ADA2) and to determine their activities with adenosine and 2'-deoxyadenosine as substrates. Km values (microM) for adenosine and 2'-deoxyadenosine, respectively, as substrates for partially purified opossum liver adenosine deaminase isoenzymes were ADA1: 57 +/- 7 vs. 26 +/- 4 and ADA2: 285 +/- 25 vs.

Plasma adenosine deaminase2 is a marker for human immunodeficiency virus-1 seroconversion.

Plasma adenosine deaminase2 (ADA2) has recently been proposed to be a marker for human immunodeficiency virus-1 (HIV) infection. We measured ADA2 levels in plasma from two groups of white homosexual males at 6-month intervals for a total of 2.5 years.

Structure-activity relationship of ligands of human plasma adenosine deaminase2.

Diethylaminoethyl-cellulose chromatography was used to separate the two isoenzymes of adenosine deaminase (EC3.5.4.

Plasma adenosine deaminase2: a marker for human immunodeficiency virus infection.

Plasma concentrations of the two isoenzymes of adenosine deaminase (ADA, E.C. 3.

Uridine phosphorylase from Schistosoma mansoni.

Uridine phosphorylase is the only pyrimidine nucleoside cleaving activity that can be detected in extracts of Schistosoma mansoni. The enzyme is distinct from the two purine nucleoside phosphorylases contained in this parasite. Although Urd is the preferred substrate, uridine phosphorylase can also catalyze the reversible phosphorolysis of dUrd and dThd, but not Cyd, dCyd, or orotidine.

Effects of N,N-dimethylformamide and sodium butyrate on enzymes of pyrimidine metabolism in cultured human tumor cells.

Effects of a 7-day treatment with the maturational agents DMF and sodium butyrate on enzymes of pyrimidine metabolism, growth rate and cell maturation were assessed in 5 human tumor cell lines, ARH-77 (myeloma), K-562 (chronic myeloid leukemia), KG-1 (myeloid leukemia), HL-60 (promyelocytic leukemia) and RWLy-1 (non-Hodgkin's lymphoma). DMF lengthened the doubling times of all five cell lines while sodium butyrate lengthened only those of K-562, HL-60 and RWLy-1. Full maturation was induced only in HL-60 by either agent and in K-562 by butyrate.

Structure-activity relationship of pyrimidine base analogs as ligands of orotate phosphoribosyltransferase.

Eighty pyrimidine base analogs were evaluated as inhibitors of mouse liver orotate phosphoribosyltransferase (OPRTase, EC 2.4.2.

Enzymes of uridine 5'-monophosphate biosynthesis in Schistosoma mansoni.

In Schistosoma mansoni, the major product of in vitro orotate metabolism was orotidine 5'-monophosphate (OMP), whereas in mouse liver it was UMP. In contrast to mammalian cells, OMP appeared not to be 'channeled' from orotate phosphoribosyltransferase to OMP decarboxylase in S. mansoni, resulting in substantial degradation of OMP to orotidine.

Structure-activity relationship of ligands of the pyrimidine nucleoside phosphorylases.

Eighty-seven pyrimidine base and nucleoside analogs were evaluated as inhibitors of uridine phosphorylase (UrdPase) and thymidine phosphorylase (dThdPase). These findings, together with an extensive literature review, have allowed construction of structure-activity relationships for the binding of ligands to UrdPase and dThdPase and provide a basis for the rational design of new inhibitors of these enzymes. Additionally, 2,6-pyridinediol and 6-benzyl-2-thiouracil have been identified as being potent inhibitors of UrdPase and dThdPase respectively.

5-benzylacyclouridine and 5-benzyloxybenzylacyclouridine, potent inhibitors of uridine phosphorylase.

Various pyrimidine acyclonucleosides (1-(2'-hydroxyethoxymethyl)uracils) are specific inhibitors of uridine phosphorylase[Niedzwicki et al., Biochem. Pharmac.