Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzymes that catalyse the salvage of purines in Entamoeba histolytica trophozoites have been surveyed. Adenine deaminase (EC 3.5.4.2), adenosine deaminase (EC 3.5.4.4), guanine deaminase (EC 3.5.4.3), adenine phosphoribosyltransferase (PRTase) (EC 2.4.2.7), xanthine PRTase (EC 2.4.2.22) and hypoxanthine PRTase (EC 2.4.2.8) were all detected in cell homogenates but only at low activities, whereas AMP deaminase (EC 3.5.4.6) and guanine PRTase (EC 2.4.2.8) were not found. Phosphorylases (EC 2.4.2.1) active in both anabolic and catabolic directions were present and all nucleosides tested were phosphorylated by kinases (EC 2.7.1.15, EC 2.7.1.20, EC 2.7.1.73). 3'-Nucleotidase (EC 3.1.3.6) and 5'-nucleotidase (EC 3.1.3.5) were found, the former being mainly particulate. Nucleotide interconversion enzymes (adenylosuccinate lyase, EC 4.3.2.2; adenylosuccinate synthetase, EC 6.3.4.4; IMP dehydrogenase, EC 1.2.1.14; GMP synthetase, EC 6.3.5.2 and GMP reductase, EC 1.6.6.8) were not detected. The results suggest that in E. histolytica the main route of nucleotide synthesis is from the individual bases through the actions of phosphorylases and kinases.
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PMID:Purine-metabolising enzymes in Entamoeba histolytica. 287 91

Extracts of Babesia divergens were examined for the enzymes which catalyse purine salvage. Adenosine deaminase (EC 3.5.4.4), guanine deaminase (EC 3.5.4.3), inosine phosphorylase (EC 2.4.2.1), purine phosphoribosyltransferases (EC 2.4.2.7, EC 2.4.2.8, EC 2.4.2.22) and nucleoside kinases (EC 2.7.1.15, EC 2.7.1.20, EC 2.7.1.73) were all detected at relatively high activities, whereas nucleotide interconverting enzymes were not detected. Coformycin and 4-amino-5-imidazolecarboxamide were found to be potent inhibitors of adenosine deaminase and guanine deaminase, respectively. The results suggest that B. divergens is capable of synthesizing purine nucleotides via two routes, one involving purine phosphoribosyltransferases and the other employing nucleoside kinases.
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PMID:Purine-metabolizing enzymes in Babesia divergens. 303 31

RNAs, more than ever before, are increasingly viewed as biomolecules of the future, in the versatility of their functions and intricate three-dimensional folding. To effectively study them by nuclear magnetic resonance (NMR) spectroscopy, structural biologists need to tackle two critical challenges of spectral overcrowding and fast signal decay for large RNAs. Stable-isotope nucleotide labeling is one attractive solution to the overlap problem. Hence, developing effective methods for nucleotide labeling is highly desirable. In this work, we have developed a facile and streamlined source of recombinant enzymes from the pentose phosphate pathway for making such labeled nucleotides. The Escherichia coli (E. coli) genes encoding ribokinase (RK), adenine phosphoribosyltransferase (APRT), xanthine/guanine phosphoribosyltransferase (XGPRT), and uracil phosphoribosyltransferase (UPRT) were sub-cloned into pET15b vectors. All four constructs together with cytidine triphosphate synthetase (CTPS) and human phosphoribosyl pyrophosphate synthetase isoform 1 (PRPPS) were transformed into the E. coli BL21(AI) strain for protein over-expression. The enzyme preparations were purified to >90% homogeneity by a one-step Ni-NTA affinity chromatography, without the need of a further size-exclusion chromatography step. We obtained yields of 1530, 22, 482, 3120, 2120 and 2280 units of activity per liter of culture for RK, PRPPS, APRT, XGPRT, UPRT and CTPS, respectively; the specific activities were found to be 70, 22, 21, 128, 144 and 113 U/mg, respectively. These specific activities of these enzyme constructs are comparable to or higher than those previously reported. In addition, both the growth conditions and purification protocols have been streamlined so that all the recombinant proteins can be expressed, purified and characterized in at most 2 days. The availability and reliability of these constructs should make production of fully and site-specific labeled nucleotides for making labeled RNA accessible and straightforward, to facilitate high-resolution NMR spectroscopic and other biophysical studies.
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PMID:Expression, purification and analysis of the activity of enzymes from the pentose phosphate pathway. 2111 Oct 48