Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.53 (sialidase)
 2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transferrin is N-glycosylated glycoprotein and plays an important role in iron transport from sites of absorption and storage to sites of utilization. Chronic ethanol alters the normal microheterogeneity pattern of transferrin as a consequence of changes in the sialic acid content. However the underlying basis of this change in sialic acid contents of transferrin in alcohol abuse remains unclear. We have undertaken this study in order to investigate the effects of chronic ethanol in rats with respect to the hepatic rate of (i) transferrin synthesis based on labeled leucine incorporation, (ii) the incorporation of labeled N-acetyl mannosamine (NAM) into sialic acid residues of transferrin, and (iii) roles of specific sialyltransferase and sialidase at hepatic subcellular level. The results showed no significant difference in the incorporation of labeled leucine into transferrin at all levels between the control and ethanol group, whereas the incorporation of NAM into transferrin was significantly decreased by 84% (p < 0.001) both at the whole cell and Golgi level. Thus, the incorporation of labeled NAM relative to the incorporation of labeled leucine into hepatic transferrin was significantly decreased by 86% (p < 0.001) in chronic ethanol-treated animals as compared with the controls both at the whole cell golgi levels. These data are further supported by our finding of concomitant decrease in the activity of beta-galactoside alpha 2,6-sialyltransferase by 58% (p < 0.01) in ethanol-treated rats as compared with control animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of chronic ethanol on enzymes regulating sialylation and desialylation of transferrin in rats. 833 87

One of the biochemical characteristics of carbohydrate deficient glycoprotein syndromes is the presence of abnormal glycoforms in serum transferrin. Both glycoform heterogeneity and variable site occupancy may, in principle, lead to the generation of a range of glycoforms which contain different numbers of sialic acid residues, and therefore variable amounts of negative charge. Capillary zone electrophoresis was used to resolve the glycoforms of normal human serum transferrin and also of a set of glycoforms which were prepared by digesting the sugars on the intact glycoprotein with sialidase. The sugars on the intact glycoprotein were also modified by a series of exoglycosidase enzymes to produce a series of neutral glycoforms which were-also analysed by capillary zone electrophoresis. The oligosaccharide population of human serum transferrin was analysed by a series of mixed exoglycosidase digests on the released glycan pool and quantified using a novel HPLC strategy. Transferrin was isolated from carbohydrate deficient glycoprotein syndromes type I serum and both the intact glycoforms and released sugars were resolved and quantified. The data presented here confirm the presence of a hexa-, penta- and tetra-sialoforms of human serum transferrin in both normal and carbohydrate deficient glycoprotein syndrome type I serum samples. Consistent with previous reports carbohydrate deficient glycoprotein syndrome type I transferrin also contained a di-sialoform, representing a glycoform in which one of the two N-glycosylation sites is unoccupied, and a non-glycosylated form where both remain unoccupied. This study demonstrates that capillary zone electrophoresis can be used to resolve quantitatively both sialylated and neutral complex type glycoforms, suggesting a rapid diagnostic test for the carbohydrate deficient glycoprotein syndromes group of diseases.
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PMID:The identification of abnormal glycoforms of serum transferrin in carbohydrate deficient glycoprotein syndrome type I by capillary zone electrophoresis. 898 Oct 95

Transferrin is a N-glycosylated glycoprotein and plays an important role in iron transport from sites of absorption and storage to sites of utilization. The main component of normal serum transferrin contains two biantennary glycans, each consisting of 2 mol of sialic acid (Tetrasialo transferrin). Normal serum also contains small amounts of tri- and disialotransferrin. We have undertaken this study to investigate the levels of serum carbohydrate-deficient transferrin (Desialotransferrin) and sialidase levels in patients with coronary heart disease. In patient group, serum desialotransferrin and sialidase levels were found to be significantly higher than control group (p < 0.01 and p < 0.001, respectively). We conclude that increased activity of sialidase may be responsible for increased desialotransferrin in patients with coronary heart disease. Serum desialotransferrin levels may be useful critaria to diagnosis and pathogenesis of coronary heart disease.
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PMID:Carbohydrate-deficient transferrin and sialidase levels in coronary heart disease. 1096 81

Carbohydrate deficient transferrin (CDT) is one of the conventional markers for chronic alcohol consumption, is used by researchers and clinicians. A number of enzymes are affected by ethanol intake. The induction or inhibition of sialyl transferase and plasma sialidase may be involved in the CDT level elevation. An alteration of protein transport during post-translational modification could be a primary mechanism in the impairment of protein metabolism associated with chronic alcohol abuse. Transferrin being a steroid responsive protein, sex-based hormonal variations might contribute to the lower sensitivity of CDT. Varying hormonal statuses such as pregnancy, use of contraceptives, menopause/ menstrual cycle can alter iron homeostasis in women. CDT levels are markedly affected by iron homeostasis. Several CDT assay methods appeared promising, but it is not readily apparent which technique is the most accurate. Moreover, false-positive results of CDT have been reported in non-alcohol related hepatic failure and in rare conditions. Therefore clinical interpretation of CDT needs careful assessment in patients with alcohol-related or non-alcohol-related health disorders.
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PMID:Should we use carbohydrate deficient transferrin as a marker for alcohol abusers? 2310 54