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

---

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

1. Cytidine-5'-monophospho-N-acetylneuraminic acid: (galactosyl-N-acetyl-galactosaminyl-(N-acetylneuraminyl)-galactosyl-glucosylceramide sialyltransferase (CMP-NAcNeu: monosialoganglioside (GM1) sialyltransferase) activity was demonstrated in the neurohypophysis of the rabbit. 2. Optimum activity occurred at pH 6.5 and required the presence of exogenous galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosyl-glucosylceramide (GM1 ganglioside), detergent (Triton X-100), and divalent cation (Mn2+, Mg2+ or Ca2+). 3. The product of the reaction was characterized as N-acetylneuraminyl-galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosyl-glucosylceramide (GD1a) by ascending thin-layer chromatography. 4. Physiological stimulation of vasopressin secretion, by the substitution of 2.2% NaCl for drinking water for 14 days, had no effect on the enzyme activiity or the ganglioside content of the tissue.
...
PMID:Cytidine-5'-monophospho-N-acetylneuraminic acid galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosyl-glucosylceramide sialyltransferase in the neurohypophysis of the rabbit. 0 25

A glycosyltransferase, CMP-N-acetylneuraminic acid : glycoprotein sialyltransferase was found in human malignant melanoma. Activities were measured with desialized glycoprotein as an exogenous acceptor. The enzyme was characterized by means of its pH optimum, 5.5, temperature optimum, 30 degrees C, KM values, 10 muM for the sugar nucleotide and 0.3 mM for desialized glycoprotein. It did not require exogenously added metal ions but was slightly stimulated by Mg2+. It required detergent for optimal activity. The effect of nucleotides and sugar nucleotides on enzyme activity has been investigated.
...
PMID:[Sialyltransferase in human malignant melanoma]. 1 Jan 4

The sialyltransferase (= glycoprotein-sialic acid transferase) was studied in the sponge Geodia cydonium, a mesozoan organism. The experiments were performed both in intact cellular and in isolated enzyme systems. It is shown, that desialylated cells show a lower aggregation potency than the controls. During aggregation enzymic sialylation of desialylated sponge cells occurs in the presence of an aggregation factor, which is associated with a high molecular weight particle. The sialylation process is temperature-dependent and can be inhibited by N-ethylmaleimide. Sialylation occurs predominantly at a distinct cell surface component, the aggregation receptor. The sialyltransferase was isolated and purified by the following steps: Sepharose 4B, CM-cellulose, Nonidet treatment, and Sephadex G-100. By this procedure the enzyme was purified 680-fold with a 31% yield. The sialyltransferase is originally associated with the high molecular weight particle also carrying the aggregation factor. In the last step the aggregation factor was separated from the sialyltransferase. The enzyme catalyzes the transfer of sialic acid from CMP-sialic acid to the desialylated aggregation receptor. The molecular weight of the sialyltransferase has been determined to be 52,000. Kinetic studies revealed no lag phase and a dependence on enzyme concentration. The purified transferase has a pH optimum of 7.75 and requires 200 mM NaCl for activity. No requirement for Mg2+ or Ca2+ could be observed. The reaction is inhibited by 10 micronM N-ethylmaleimide.
...
PMID:Species-specific aggregation factor in sponges. Sialyltransferase associated with aggregation factor. 1 20

An enzyme preparation from embryonic chicken brain catalyzes the transfer of sialic acid from CMP-N-acetylneuraminic acid to ceramide-Glc-Gal(NeuAc-NeuAc)-GalNAc-Gal (GDlb) to form ceramide-Glc-Gal(NeuAc-NeuAc)-GalNAc-Gal-NeuAc (GTlb). The sialyltransferase activity was measured during the development of the embryo, the subcellular distribution of this activity was determined and several kinetic properties of the reaction were examined. A comparative study with the similar reaction involved in the transfer of sialic acid to the terminal galactose in ceramide-Glc-Gal(NeuAc)-GalNAc-Gal (GMl) was made. The results obtained in this comparative study suggest that the transfer of sialic acid in both reactions is catalyzed by the same enzyme.
...
PMID:Trisialoganglioside synthesis by a chicken brain sialyltransferase. Comparative study with the similar reaction for the synthesis of disialoganglioside. 1 68

A cell-free system was established to study the biosynthesis of group C meningococcal capsular polysaccharide, an alpha-2 leads to 9-linked N-acetylneuraminic acid (NeuAc) homopolymer containing O-acetyl groups at either C7 or C8. Sialyltransferase activity, isolated from group C meningococcus strain C-11, catalyzed incorporation of [14C]NeuAc from CMP (CMP--[14C]NeuAc) into polymeric form. This sialyltransferase was stimulated by addition of meningococcus group C and Escherichia coli K92 capsular polysaccharides, the latter being an alpha-2 leads to 8- and alpha-2 leads to 9-linked NeuAc heteropolymer. Group C meningococcal sialyltransferase did not require divalent ions but was stimulated by Mn2+. Attempts to demonstrate a lipid-soluble intermediate in the biosynthesis of this NeuAc polymer were unsuccessful. Meningococcal group C sialyltransferase incorporated NeuAc into a membrane-associated product. The polysaccharide can be extracted from the membrane-bound fraction with Triton X-100. The newly synthesized polysaccharide coprecipitates with authentic group C antigen in meningococcal group C antiserum and is degraded by sodium metaperiodate, indicating that the NeuAc polymer synthesized by the cell-free system consists of alpha-2 leads to 9 linkage. Meningococcal group C spheroplast membranes contain an O-acetylase that can catalyze the transfer of acetyl groups from acetyl coenzyme A to the in vitro-synthesized polysaccharide.
...
PMID:Cell-free biosynthesis of the O-acetylated N-acetylneuraminic acid capsular polysaccharide of group C meningococci. 2 63

CMP-AcNeu:glycoprotein sialyltransltransltransltransltransferase of calf kidney cortex was characterized using serum glycoproteins and Tamm-Horsfall glycoprotein, obtained from calf urine, as acceptors. Native calf Tamm-Horsfall glycoprotein showed the best acceptor properties, followed by desialylated calf fetuin and desialylated human alpha 1-acid glycoprotein exhibiting V values of, respectively, 114, 63 and 41 nmol/h per g wet wt. of kidney cortex and Km values of 0.12, 0.16 and 0.26 mM glycoprotein acceptor. Desialylated ovine submaxillary mucine appeared to be a very poor acceptor. Tamm-Horsfall glycoprotein sialyltransferase could be distinguished from serum glycoprotein sialyltransferase by competition studies. In addition the two glycoprotein sialyltransferase activities showed different distributions over the three regions of the calf kidney: the ratios of the Tamm-Horsfall to serum glycoprotein sialyltransferase activities decreased from 3.3 in the cortex to 0.8 and 0.4 in the medulla and the papilla, respectively. It was concluded that in calf kidney at least two different sialyltransferases exist. The high cortical Tamm-Horsfall glycoprotein sialyltransferases activity corresponds markedly to the origin of the urinary Tamm-Horsfall glycoprotein, namely the distal part of the kidney tubule. Inactivation of glycoprotein sialyltransferase activity by preincubation at various temperatures and during storage at 0 degree C, could be reduced by the addition of CMP-AcNeu. The possible relevance towards the in vivo sialylation of this finding is discussed.
...
PMID:Glycoprotein biosynthesis in calf kidney. Glycoprotein sialyltransferase activities towards serum glycoproteins and calf Tamm-Horsfall glycoprotein. 3 73

Sialyltransferase(s) activity [CMP-N-acetylneuraminic acid:glycoprotein sialyltransferase(s) E.C. 2.4.99.1] was assayed using asialofetuin as a substrate in a total microsomal fraction obtained from rat liver. Rats pretreated with phenobarbital or methylcholanthrene demonstrated a decrease in membrane bound sialyltransferase(s) activity of 27% and 18%,respectively. Microsomes prepared from phenobarbital treated rats were incubated in vitro with aflatoxins B1, B2, B2a, G1, or G2 in the presence or absence of an NADPH generating system. Following this treatment the microsomes were reisolated, washed and assayed for sialyltransferase(s) activity. Aflatoxin B1 and B2a inhibited sialyltransferase(s) by 46% and 55%, respectively, while aflatoxin G1 inhibited sialyltransferase(s) by 54%. Aflatoxins B2 and G2 were only slightly inhibitory. It is proposed that the enzyme inhibition caused by these various aflatoxins is due to binding of these agents to the membranes resulting in a local disruption of the membrane and a change in enzyme conformation.
...
PMID:Differential inhibition of rat liver sialyltransferase(s) by various aflatoxins and their metabolites. 5 Jun 14

We synthesized on Tn erythrocytes with human sera, UDP-Gal, and activators T-specific haptenic structures in satisfactory yield. The specificity of this biosynthesis was ascertained by agglutination with human and animal anti-T, by specific absorption of human anti-T as well as by agglutination inhibition assays. With isolated human erythrocyte T antigen as substrate we synthesized N- and M-specific structures with sera from individual human donors in presence of CMP-sialic acid by incubation for 24 hr at 37 degrees C. Serology on the recovered product was carried out with nineteen monospecific human and animal sera under strictly standardized and controlled conditions with the mandatory tube assay. All M- as well as N-derived T antigens tested acquired N specificity with all transferase sera of all MN types. In contrast, M-activation of M- and N-drived T antigens tested acquired N specificity with all transferase sera of all MN types. In contrast, M-activation of M- and N-derived T antigens occurred only if the transferase donor had the M gene. The nine M transferase sera used all gave M-activation of MM- and NN-derived T antigens. None of twelve transferase sera from NN donors M-activated any T antigen. NN antigen was transformed to a M-specific one by all transferase sera from MM donors but by none from NN donors. We have not yet established the biochemical-genetic relation of M to N; N may be the immediate precursor of M or M may originate directly from T. The sialyltransferase responsible for M activation may be a N transferase 'modified' by the M gene product or an entirely different sialyltransferase.
...
PMID:Biosynthesis of human blood group T-, N- and M-specific immunodeterminants on human erythrocyte antigens. 9 34

Human factor VIII/von Willebrand factor protein containing 120 +/- 12 nmol of sialic acid and 135 +/- 13 nmol of galactose/mg of protein was digested with neuraminidase. The affinity of native factor VIII/von Willebrand factor and its asialo form for the hepatic lectin that specifically binds asialoglycoproteins was assessed from in vitro binding experiments. Native factor VIII/von Willebrand factor exhibited negligible affinity while binding of the asialo derivative was comparable to that observed for asialo-alpha1-acid glycoprotein. Incubation of asialo-factor VIII/von Willebrand factor with Streptococcus pneumoniae beta-galactosidase removed only 62% of the galactose but abolished binding to the purified hepatic lectin. When the asialo derivative was incubated with purified beta-D-galactoside alpha2 leads to 6 sialyltransferase and CMP-[14C]NeuAc, only 61% of the galactose incorporated [14C]NeuAc. From the known specificites of these enzymes, it is concluded that galactose residues important in lectin binding are present in a terminal Gal/beta1 leads to 4GlcNAc sequence on asialo-factor VIII/von Willebrand factor. The relative ristocetin-induced platelet aggregating activity of native, asialo-, and agalacto-factor VIII/von Willebrand factor was 100:38:12, respectively, while procoagulant activity was 100:100:103.
...
PMID:Carbohydrate on human factor VIII/von Willebrand factor. Impairment of function by removal of specific galactose residues. 10 Apr 92

Mouse cells transformed by a temperature-sensitive mutant of simian virus 40 belonging to complementation group A lost their ability to regulate cell growth when grown at the permissive temperature (35 degrees) but showed the low saturation density of cell growth at the restrictive temperature (39.5 degrees) that is characteristic of normal cells in vitro. Biochemical analysis of the membranes of cells grown under the restrictive and the permissive conditions demonstrated no qualitative temperature-dependent differences either in neutral glycolipids or in acidic glycolipids of the cells. Plasma membrane glycoproteins labeled with radioactive glucosamine showed significantly different patterns on both polyacrylamide gel electrophoresis and electrofocusing. When the levels of glycoprotein glycosyltransferases of the cells were examined, the level of sialyltransferase (CMP-N-acetylneuraminytransferase,EC 2.4.99.1) of the cells grown at the restrictive temperature was low compared with that of cells grown at the permissive temperature. Our results indicate that the level of sialyltransferase is under the control of the gene A function of simian virus 40 and consequently is related to alterations in the cell surface glycoproteins.
...
PMID:Alterations in surface glycoproteins and level of sialyltransferase of cells transformed by a temperature-sensitive mutant of simian virus 40. 18 85


1 2 3 4 5 6 7 8 9 10 Next >>

---