Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.99.6 (sialyltransferase)
 1,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple preparation of the "core-II" N-acetylglucosaminyltransferase (UDP-D-GlcpNAc:beta-D-Galp-(1-->3)-alpha-D-GalpNAc (GlcNAc to GalNAc) beta-(1-->6)-GlcNAc-transferase, GlcNAcT, EC 2.4.1.102) from commercial mouse kidney acetone powder is reported. The enzyme obtained in a single step of affinity chromatography is suitable for use in preparative oligosaccharide synthesis. In conjunction with previously described preparations of beta-(1-->4)-galactosyltransferase (EC 2.4.1.22), alpha-(2-->3)-sialytransferase (EC 2.4.99.6) and alpha-(1-->3/4)-fucosyltransferase (EC 2.4.1.65), the GlcNAcT was used in the first step of a sequence which converted the disaccharide beta-D-Galp-(1-->3)-alpha-D-GalpNAc-OR into the sialyl-LeX-containing structure alpha-D-NeupAc-(2-->3)-beta-D-Galp- (1-->4)-[alpha-L-Fucp-(1-->3)]-beta-D-GlcpNAc-(1-->6)-[beta-D-Galp - (1-->3)]-alpha-D-GalpNAc-OR (5), where R = (CH2)8CO2Me. Hexasaccharide 5, thus assembled in only one week once the enzymes were prepared, was characterized by 1H and 13C NMR spectroscopy and fast-atom bombardment mass spectrometry, as were all intermediate oligosaccharides. The core II GlcNAcT thus joins the expanding repertoire of readily available reagents for the rapid assembly of oligosaccharides.
 ...
PMID:Use of the "core-2"-N-acetylglucosaminyltransferase in the chemical-enzymatic synthesis of a sialyl-LeX-containing hexasaccharide found on O-linked glycoproteins. 810 68

To elucidate control mechanisms of O-glycan biosynthesis in leukemia and to develop biosynthetic inhibitors we have characterized core 2 UDP-GlcNAc:Gal beta 1-3GalNAc-R(GlcNAc to GalNAc) beta 6-N-acetylglucosaminyltransferase (EC 2.4.1.102; core 2 beta 6-GlcNAc-T) and CMP-sialic acid: Gal beta 1-3GalNAc-R alpha 3-sialyltransferase (EC 2.4.99.4; alpha 3-SA-T), two enzymes that are significantly increased in patients with chronic myelogenous leukemia (CML) and acute myeloid leukemia (AML). We observed distinct tissue-specific kinetic differences for the core 2 beta 6-GlcNAc-T activity; core 2 beta 6-GlcNAc-T from mucin secreting tissue (named core 2 beta 6-GlcNAc-T M) is accompanied by activities that synthesize core 4 [GlcNAc beta 1-6(GlcNAc beta 1-3)GalNAc-R] and blood group I [GlcNAc beta 1-6(GlcNAc beta 1-3)Gal beta-R] branches; core 2 beta 6-GlcNAc-T in leukemic cells (named core 2 beta-GlcNAc-T L) is not accompanied by these two activities and has a more restricted specificity. Core 2 beta 6-GlcNAc-T M and L both have an absolute requirement for the 4- and 6-hydroxyls of N-acetylgalactosamine and the 6-hydroxyl of galactose of the Gal beta 1-3GalNAc alpha-benzyl substrate but the recognition of other substituents of the sugar rings varies, depending on the tissue. alpha 3-sialyltransferase from human placenta and from AML cells also showed distinct specificity differences, although the enzymes from both tissues have an absolute requirement for the 3-hydroxyl of the galactose residue of Gal beta 1-3GalNAc alpha-Bn. Gal beta 1-3(6-deoxy)GalNAc alpha-Bn and 3-deoxy-Gal beta 1-3GalNAc alpha-Bn competitively inhibited core 2 beta 6-GlcNAc-T and alpha 3-sialyltransferase activities, respectively.
 ...
PMID:Processing O-glycan core 1, Gal beta 1-3GalNAc alpha-R. Specificities of core 2, UDP-GlcNAc: Gal beta 1-3 GalNAc-R(GlcNAc to GalNAc) beta 6-N-acetylglucosaminyltransferase and CMP-sialic acid: Gal beta 1-3GalNAc-R alpha 3-sialyltransferase. 829 5