Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A nonradioactive multiwell spectrophotometric assay for the interferon-induced enzyme 2',5'-oligoadenylate synthetase measuring the inorganic pyrophosphate produced during oligoadenylate synthesis has been developed. A coupled enzymatic reaction results in a mole to mole formation of NADPH compared to the inorganic pyrophosphate through the use of the three enzymes UDP-Glc pyrophosphorylase (EC2.7.7.9), phosphoglucomutase (EC5.4.2.2), and glucose-6-phosphate dehydrogenase (EC1.1.1.49). The assay is at least as sensitive for measurements of 2',5'-oligoadenylate synthetase activity as the conventional assays using radioactive nucleotides as substrates. Even higher sensitivity of the assay can be obtained by taking advantage of the strong fluorescence of NADPH.
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PMID:Spectrophotometric pyrophosphate assay of 2',5'-oligoadenylate synthetase. 133 38

Sialylation, the attachment of sialic acid residues to a protein, can affect the biological activity and in vivo circulatory half-life of glycoproteins. Human alpha2,3- sialyltransferase (alpha2,3-ST) and beta1,4-galactosyltransferase (beta1,4-GT) are responsible for terminal sialylation and galactosylation, respectively. Enhanced sialylation of human erythropoietin (EPO) by the expression of alpha2,3-ST and beta1,4-GT was achieved using recombinant Chinese hamster ovary (CHO) cells (EC1). The sialic acid content and sialylation of N-glycans were evaluated by HPLC. When alpha2,3-ST was expressed in CHO cells (EC1-ST2), the sialic acid content (moles of sialic acid/mole of EPO) increased from 6.7 to 7.5. In addition, the amount of trisialylated glycans increased from 17.3% to 26.1%. When alpha2,3-ST and beta1,4-GT were coexpressed in CHO cells (EC1-GTST15), the degree of sialylation was greater than that in EC1-ST2 cells. In the case of EC1-GTST15 cells, the sialic acid content increased to 8.2 and the proportion of trisialylated glycans was markedly increased from 17.3% to 35.5%. Interestingly, the amount of asialoglycans decreased only in the case of GTST15 cells (21.4% to 14.2%). These results show that coexpression of alpha2,3- ST and beta1,4-GT is more effective than the expression of alpha2,3-ST alone. Coexpression of alpha2,3-ST and beta1,4-GT did not affect CHO cell growth and metabolism or EPO production. Thus, coexpression of alpha2,3-ST and beta1,4-GT may be beneficial for producing therapeutic glycoproteins with enhanced sialylation in CHO cells.
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PMID:Enhanced sialylation of recombinant erythropoietin in CHO cells by human glycosyltransferase expression. 1913 98

Lactate dehydrogenase (LDH, EC1.1.1.27), widely expressed in the heart, liver, and other tissues, plays an important role in glycolysis and glyconeogenesis. The activity of LDH is often altered upon inflammatory responses in animals. Nano-TiO(2) was shown to provoke various inflammatory responses both in rats and mice; however, the molecular mechanism by which TiO(2) exerts its toxicity has not been completely understood. In this report, we investigated the mechanisms of nano-anatase TiO(2) (5 nm) on LDH activity in vitro. Our results showed that LDH activity was greatly increased by low concentration of nano-anatase TiO(2), while it was decreased by high concentration of nano-anatase TiO(2). The spectroscopic assays revealed that the nano-anatase TiO(2) particles were directly bound to LDH with mole ratio of [nano-anatase TiO(2)] to [LDH] was 0.12, indicating that each Ti atom was coordinated with five oxygen/nitrogen atoms and a sulfur atoms of amino acid residues with the Ti-O(N) and Ti-S bond lengths of 1.79 and 2.41 A. We postulated that the bound nano-anatase TiO(2) altered the secondary structure of LDH, created a new metal ion-active site for LDH, and thereby enhanced LDH activity.
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PMID:The effects of nano-anatase TiO(2) on the activation of lactate dehydrogenase from rat heart. 1921 98