Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.4.99.7 (sialyltransferase)
1,534 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two different sialyltransferases (EC 2.4.99.1) have been resolved from Triton X-100 extracts of porcine submaxillary glands by affinity chromatography on CDP-hexanolamine agarose. The predominant sialyltransferase of this tissue, a CMP-N-acetylneuraminate: alpha-D-N-acetylgalactosaminide alpha2 leads to 6 sialyltransferase, has been obtained in a partially purified and stable form. A less abundant but highly active enzyme, a CMP-N-acetylneuraminate: beta-D-galactoside alpha2 leads to 3 sialyltransferase, was purified over 90,000-fold to homogeneity. Chromatography of the latter enzyme on Sephadex G-200 separated two noninterconverting forms, designated A and B, with Stokes radii of 51 A and 31 A, respectively. Both forms have equal specific activity toward lactose and contain a single polypeptide with a molecular weight of about 50,000 as estimated by gel electrophoresis. Form A appears to bind 1.18 g of Triton X-100 per g of protein, or nearly an entire detergent micelle per polypeptide, while Form B binds little or no detergent. The enzymatic properties of both forms are similar (Rearick, J.I., Sadler, J.E., Paulson, J.C., and Hill, R.L. (1979) J. Biol. Chem. 254, 4444-4451) supporting the conclusion that Form A may represent the native sialyltransferase with an intact membrane-binding site, and Form B may be a large proteolytic fragment of Form A.
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PMID:Purification to homogeneity of a beta-galactoside alpha2 leads to 3 sialyltransferase and partial purification of an alpha-N-acetylgalactosaminide alpha2 leads to 6 sialyltransferase from porcine submaxillary glands. 43 96

Sialyltransferase activity in normal human breast tissue and tumors was investigated with lactose, desialylated fetuin, and bovine submaxillary mucin as the acceptors. While microsomal preparations from the normal tissue showed little or no sialyltransferase activity toward these acceptors, tumors showed elevated enzymic activities. Tween-20 at 0.5% concentrations stimulated sialic acid transfer to all three acceptors. Another nonionic detergent, Triton X-100, stimulated asialo fetuin sialyltransferase activity while inhibiting activity toward asialo BSM and lactose. Interestingly, lysolecithin, a normal cellular constituent which possesses detergent properties also had an effect similar to that of Triton X-100. Thermal denaturation curves of enzymic activity toward asialo BSM, however, resembled those seen with asialo fetuin as the acceptor. Kinetic studies showed that at acceptor concentrations of 500 micrograms each, sialyl transfers to asialo fetuin, asialo BSM, and lactose showed apparent Km values of 50, 60, and 300 microM, respectively. At CMP-sialic acid concentrations of 300 microM, the Km values for the above acceptors were 25, 15, and 5000 microM.
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PMID:Some biochemical properties of human breast tumor sialyltransferase. 258 61

A new fluorogenic acceptor for sialyltransferase, 2-[(2-pyridyl)amino]ethyl O-beta-D-galactopyranosyl-(1----4)-beta-D-glucopyranoside, was prepared from lactose as a starting material. Sialyltransferase activity was assayed by incubation of the enzyme with the acceptor and CMP-N-acetylneuraminic acid, separation of the fluorogenic sialylated product from the enzymatic reaction mixture by HPLC, and measurement of the product. Compared to assays so far reported that use radioactive substrates, this assay is simple and rapid. This method was used to assay sialyltransferase activity in human serum.
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PMID:Simple assay for sialyltransferase activity with a new fluorogenic substrate. 322 Aug 27

As described previously (I. Kijima-Suda et al., Cancer Res., 46: 858-862, 1986), a sialyltransferase inhibitor, 5-fluoro-2',3'-isopropylidene-5'-O-(4-N-acetyl-2,4-dideoxy-3,6,7,8-tetra -O- acetyl-1-methoxycarbonyl-D-glycero-alpha-D-galactooctapyranosyl)ur idine (KI-8110), inhibits pulmonary metastasis of murine colon adenocarcinoma 26 sublines of high (NL-17) and low (NL-44) metastatic potential. To investigate the mechanism of this inhibition, the effect of KI-8110 on the metastatic cascade, especially on the interaction between tumor cells and platelets which may play a crucial role in tumor cell metastasis, was examined. NL-17 cells induced irreversible platelet aggregation in heparinized human platelet-rich plasma in vitro. This activity was reduced by pretreatment of the tumor cells with KI-8110. Inhibition of aggregation was also induced by the treatment of tumor cells with neuraminidase or Limax flavus agglutinin, a lectin specific for sialic acid. Sialic acid, fucose, sialyllactose, and bovine submaxillary mucin inhibited this tumor cell-induced platelet aggregation, while galactose, mannose, lactose, alpha 1-acid glycoprotein, fetuin, and asialo-bovine submaxillary mucin did not. KI-8110 also inhibited platelet-derived growth factor-dependent growth of NL-17 cells, but showed no effect on insulin or epidermal growth factor-dependent growth of the tumor cells. Platelet-derived growth factor-induced phosphorylation of membrane protein was reduced by treatment of NL-17 cells with KI-8110. The same result was obtained in the neuraminidase-treated membrane fraction of NL-17 cells. These results suggest that KI-8110 inhibits experimental tumor cell metastasis by inhibiting the interaction between tumor cells and host platelets in at least two pathways, and this may be due to a reduction of sialic acid contents of the membrane surface of tumor cells.
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PMID:Possible mechanism of inhibition of experimental pulmonary metastasis of mouse colon adenocarcinoma 26 sublines by a sialic acid: nucleoside conjugate. 328 33

A modified high pressure liquid chromatographic method using lactose (Gal beta 1----4Glc) as an exogenous acceptor has been used to characterize the sialyltransferases known to increase in the serum of colchicine-treated rats. The results show a 10-fold increase of Gal beta 1----4GlcNAc alpha 2----6 sialyltransferase (alpha 2----6 ST), whereas the Gal beta 1----3GlcNAc alpha 2----3 sialyltransferase showed only 1.6-fold increase in the serum after 17 h of colchicine treatment. The sialyltransferase activity in serum using exogenous desialylated, alpha 1-acid glycoprotein as acceptor also showed an eightfold increase. In liver homogenate and Golgi membrane, the sialyltransferase activity when assayed with desialylated alpha 1-acid glycoprotein as acceptor showed a slight decrease after 4 h, but returned to normal level after 17 h. A similar trend was seen when the two transferases were assayed with lactose as acceptor. The antiserum to rat alpha 2----6 ST inhibited the sialyltransferase activity in serum, liver, and jejunal incubation medium. Jejunal sections from rats treated with colchicine for 4 h in presence of heated serum showed a decrease of sialyltransferase, with consequent increase of the alpha 2----6 ST enzyme activity in the medium. This result suggests that intestinal tissue could be a source of increased serum enzyme activity in colchicine treatment.
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PMID:Characterization of serum, liver, and intestinal sialyltransferases from rats treated with colchicine. 358 Jan 69

Sialyltransferase activity of bovine serum with the acceptor asialofetuin exhibits a pH optimum at 6.0-6.5, no divalent cation dependence, and a Km for CMP-sialic acid of 0.05 mM. Although a 2-fold increase in sialyltransferase activity with the acceptor asialofetuin is observed in serum samples from 2-day-old vs 20-day-old calves, the relative activity towards other glycoprotein acceptors is not different between the groups. With the acceptor lactose, the major product (greater than 95%) for all samples is 3'-sialyllactose, suggesting that the elevated levels of sialyltransferase in 2-day-old calves are due to Gal-R (alpha 2-3) sialyltransferase.
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PMID:Sialyltransferase of bovine serum: age- and hormone-related changes. 374 24

Turpentine induced inflammation has been shown to elevate liver sialyl- and galactosyltransferase activities (Turchen, B., Jamieson, J.C., Huebner, E., and van Caeseele, L. (1977) Can. J. Zool. 55, 1567-1571; Lombart, C., Sturgess, J., and Schachter, H. (1980) Biochem. Biophys. Acta 629, 1-12). We now report that serum sialyl-, but not galactosyltransferase activities are significantly elevated in turpentine inflammation. A liver slice system is used to demonstrate that liver releases large amounts of sialyltransferase activity into medium after inflammation, whereas only a low level of galactosyltransferase activity is released. Studies with rat and human asialo-alpha 1-acid glycoprotein as acceptors, coupled with the use of lactose to confirm the nature of the linkages formed, showed that Gal beta 1 leads to 4GlcNAc alpha 2 leads to 6 sialyltransferase is released from liver in turpentine inflammation and is mainly responsible for the elevated sialyltransferase activity found in serum. The alpha 2 leads to 6 sialyltransferase is exhibiting the properties of a typical acute phase reactant.
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PMID:Studies on the effect of inflammation on rat liver and serum sialyltransferase. Evidence that inflammation causes release of Gal beta 1 leads to 4GlcNAc alpha 2 leads to 6 sialyltransferase from liver. 641 2

A method has been developed to determine the activities of specific sialyltransferases by analysis of the products of the reaction. This method, which utilizes high performance liquid chromatography, distinguishes addition of sialic acid to the N-acetylgalactosamine vs. galactose residues of the mucin disaccharide Gal beta(1 leads to 3)GalNac, and can be used to distinguish formation of the 3'- and 6'-isomers of sialyllactose. For the bovine, ovine, and porcine submaxillary extracts, more than 95% of the activity with asialo ovine submaxillary mucin is due to formation of NeuAc alpha(2 leads to 6)GalNAc. With lactose as the acceptor, more than 95% of the alpha(2 leads to 3) isomer is produced. Activity with asialofetuin is due solely to the O-linked chain, with relative activity toward the galactose vs. GalNAc residues of 0.32, 1.5, and 0.10 for bovine, ovine, and porcine, respectively. The rat submaxillary gland extract showed equal formation of 3'- and 6'-sialyllactose, and very low activity with asialo ovine submaxillary mucin. However, at least 40% of the activity toward the Gal beta(1 leads to 3)GalNAc disaccharide of asialofetuin was directed toward the GalNAc residue. The relative preference of the N-acetylgalactosaminide alpha(2 leads to 6) sialyltransferase for a monosaccharide vs. a substituted GalNAc may play a role in regulation of chain length during mucin synthesis.
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PMID:Specificity of submaxillary gland sialyltransferases. 663 63

The MAT-B1 and MAT-C1 ascites sublines of the 13762 rat mammary adenocarcinoma differ in morphology, agglutinability with concanavalin A, and xenotransplantability. Both cell lines contain a major mucin-type glycoprotein, but the MAT-C1 (xenotransplantable) subline contains a 3-fold-greater content of sialic acid on the glycoprotein than does the MAT-B1 (nonxenotransplantable) subline. The present work indicates that whole cells of both lines incorporate radioactivity from labeled CMP-sialic acid into a component which comigrates with the major glycoprotein by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and that label incorporated by MAT-B1 cells is released by alkaline-borohydride treatment. Sialyltransferase can be purified from 250- to 400-fold by chromatography of a Triton X-100 extract of microsomes on CDP-agarose. The purified fraction of both cell lines has a Km for CMP-sialic acid of 0.40 +/- 0.10 mM with asialofetuin as the acceptor, and gives 35 to 40% of the activity with the acceptor asialotransferrin as with asialofetuin. When assayed with a variety of acceptors, the MAT-C1 extract showed higher sialyltransferase activity at a pH below 6.5 than did the MAT-B1 extract. Analysis of the products following incubation with lactose yields only 3'-sialyllactose for both cell lines. The results indicate that the differences in MAT-B1 and MAT-C1 sialyltransferase when assayed with glycoprotein acceptors are not large enough to account for the differences in sialic acid content of the two cell lines.
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PMID:Sialyltransferase of the 13762 rat mammary ascites tumor cells. 669 99

Asialofetuin sialyltransferase from Triton X-100 extracts of rat liver was resolved by phosphocellulose chromatography into two fractions, designated I and II in order of elution. When previously treated with Arthrobacter ureafaciens neuraminidase, fraction I eluted at about the same position as II while no alteration occurred in II. Primary rat hepatomas contained only a single asialofetuin sialyltransferase, identical to fraction I in chromatographic behavior. Transferases I and II were purified to near homogeneity. Transferase II, as well as neuraminidase-treated I, could be sialylated auto-catalytically, indicating that the lack of sialic acid in II is not due to the lack of a sialic-acid-accepting site. Both enzymes formed an (alpha 2 leads to 6)sialylgalactoside linkage with asialo-glycoproteins of the glycosylamine-type and with lactose, and were indistinguishable immunologically. Nevertheless, the transferases exhibited different molecular weights of 37000 (I) and 43000 (II). When heated at 50 degrees C, transferase I lost half its original activity within 20 min while II was scarcely inactivated. Kinetically, transferase I showed three-times higher affinity than II for CMP-N-acetylneuraminic acid and for desialylated plasma membrane. Asialofetuin sialyltransferase was also purified from primary rat hepatoma. The purified enzyme was identical to transferase I in every respect examined. We conclude that hepatomas contain transferase I but lack transferase II.
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PMID:Purification and characterization of beta-galactoside (alpha 2 leads to 6)sialyltransferase from rat liver and hepatomas. 675 21


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