Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.52 (fucokinase)
 40 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A radiometric assay was developed for fucokinase (ATP:6-deoxy-L-galactose 1-phosphotransferase, EC 2.7.1.52) based on the conversion of L-[14C]fucose to L-[14C]fucose 1-phosphate which is trapped and counted on ion exchange paper. This assay was used to detect the presence of a fucokinase in canine thyroid tissue which was subsequently purified 2754-fold over the crude tissue extracts. The product of the fucokinase was identified as the beta-anomer. The pH versus activity curve for the enzyme appears biphasic with optima at pH 6.5 and pH 8.25. The enzyme was shown to be highly specific for L-fucose with a Km of 2.6 - 10(-5) M at pH 8.25. It was shown to be absolutely specific for ATP as a phosphate donor with a Km of 6.3 - 10(-4) M at pH 8.25. The enzyme requires a divalent cation. Mg2+ is slightly more effective than Mn2+ in meeting this need. The molecular weight of the enzyme has been determined to be 494 000 +/- 12 400.
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PMID:Canine thyroid fucokinase. 2 Sep 62

A 23 000-fold purification of porcine fucokinase (ATP:6-deoxy-L-galactose 1-phosphotransferase, EC 2.7.1.52) has been achieved using a combination of ion-exchange, hydrophobic ligand, affinity, hydroxyapatite and molecular sieve chromatography. The enzyme was determined to have a subunit molecular weight of 78 180 +/- 4260 by sodium dodecyl sulfate chromatography and a tetrameric molecular weight of 309 200 +/- 4100 in the active state as determined by molecular sieve chromatography. The enzyme exhibits a single pH optimum at a pH value of 6.5 and gives evidence of a high order of specificity for L-fucose and ATP. The enzyme requires a divalent metal ion and this need is best satisfied by Mg2+. The activity of the enzyme is modified by a number of nucleotides. ADP is an enzyme inhibitor competitive with ATP. GDP-beta-L-fucose is also an inhibitor and appears to compete with L-fucose. GDP-alpha-D-mannose stimulates the enzyme. A possible role for the actions of these nucleotide sugars is discussed.
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PMID:Isolation and properties of porcine thyroid fucokinase. 4 Jun 2

In Escherichia coli, L-fucose is dissimilated via an inducible pathway mediated by L-fucose permease, L-fucose isomerase, L-fucose kinase, and L-fuculose 1-phosphate aldolase. The last enzyme cleaves the six-carbon substrate into dihydroxyacetone phosphate and L-lactaldehyde. Aerobically, lactaldehyde is oxidized to L-lactate by a nicotinamide adenine dinucleotide (NAD)-linked dehydrogenase. Anaerobically, lactaldehyde is reduced by an NADH-COUPLED REDUCTASE TO L-1,2-propanediol, which is lost into the medium irretrievably, even when oxygen is subsequently introduced. Propanediol excretion is thus the end result of a dismutation that permits further anaerobic metabolism of dihydroxy-acetone phosphate. A mutant selected for its ability to grow aerobically on propanediol as a carbon and energy source was reported to produce lactaldehyde reductase constitutively and at high levels, even aerobically. Under the new situation, this enzyme serves as a propanediol dehydrogenase. It was also reported that the mutant had lost the ability to grow on fucose. In the present study, it is shown that in wild-type cells the full synthesis of lactaldehyde dehydrogenase requires the presence of both molecular oxygen and a small molecule effector, and the full synthesis of lactaldehyde reductase requires anaerobiosis and the presence of a small molecule effector. The failure of mutant cells to grow on fucose reflects the impairment of a regulatory element in the fucose system that prevents the induction of the permease, the isomerase, and the kinase. The aldolase, on the other hand, is constitutively synthesized. Three independent fucose-utilizing revertants of the mutant all produce the permease, the isomerase, the kinase, as well as the aldolase, constitutively. These strains grow less well than the parental mutant on propanediol.
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PMID:Disruption of the fucose pathway as a consequence of genetic adaptation to propanediol as a carbon source in Escherichia coli. 18 64

Thyroid fucokinase is responsive to a number of metabolites which might serve in a regulatory capacity. In addition to inhibition by ADP and stimulation by GMP, fucokinase responds selectively to a series of nucleotide sugars. Of those studied, only guanine nucleotide sugars moderate the activity of the enzyme. GDP-alpha-D-mannose, GDP-alpha-D-glucose, GDP-alpha-D-rhamnose, and GDP-alpha-L-fucose on the other hand is strongly inhibitory. In the case of GDP-alpha-D-mannose stimulation, a physiological role seems possible, but the rationale is not entirely clear. The effects of GDP-beta-L-fucose, on the other hand may represent physiological control effected through feedback inhibition by and end product.
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PMID:Metabolite control of L-fucose utilization. 21 33

Studies on glycoprotein fucosylation were carried out using hippocampal slices from rat brain. These slices were incubated in the presence of the protein kinase C (PKC) activating phorbol ester, 4 beta-phorbol-12,13-dibutyrate (PDBu), or an inactive isoform, 4 alpha-phorbol-12,13-didecanoate (PDD), respectively, for 7 min followed by a 60 min pulse of [3H]fucose. PDBu caused an increase in [3H]fucose incorporation into glycoproteins by 29% as well as an activation of the fucokinase enzyme reaction by 21%. The PDBu-induced stimulation of [3H]fucose insertion into hippocampal glycoproteins was abolished by the PKC inhibitors, staurosporine and H7. The importance of a PKC-regulated glycoprotein fucosylation in mechanisms underlying changes in neuronal plasticity is discussed.
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PMID:Phorbol ester-induced changes in rat hippocampal glycoprotein fucosylation. 132 Jul 46

Induction of long-term potentiation (LTP) in hippocampal slices of rats caused an increase in both protein synthesis and glycoprotein fucosylation by 38 and 34%, respectively. The enhanced incorporation of [3H]fucose into glycoproteins observed 1 h after tetanization was abolished in the presence of the dopamine D1 receptor antagonist SCH23390 during stimulation whereas the LTP-induced increase of protein synthesis was not influenced by this drug. The enhanced insertion of [3H]fucose into hippocampal glycoproteins 1 h after tetanization was paralleled by an increase in the activity of the fucose metabolizing enzyme, fucokinase. In contrast no changes in protein and glycoprotein synthesis were detectable 5 h after tetanization of the slices. The results provide evidence that in addition to an enhanced protein synthesis a dopamine (D1) mediated increase in glycoprotein fucosylation is necessary for the maintenance of the late stage of LTP.
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PMID:The maintenance of hippocampal long-term potentiation is paralleled by a dopamine-dependent increase in glycoprotein fucosylation. 133 1

The gluconate (gnt) operon of Bacillus subtilis includes the gntR, gntK, gntP, and gntZ genes, respectively encoding the transcriptional repressor of the operon, gluconate kinase, the gluconate permease, and an unidentified open reading frame (Fujita and Fujita, 1987). We have compared the proteins encoded by the gnt operon of B.subtilis with published sequences and showed that (i) the gluconate repressor is homologous to several putative regulatory proteins in Escherichia coli, (ii) the gluconate kinase of B. subtilis is homologous to xylulose kinase, glycerol kinase and fucose kinase in E. coli (20-26% identity; 12-59 S.D.), (iii) the gluconate permease exhibits a C-terminal domain which is homologous to a hydrophobic protein encoded by an unidentified open reading frame (dsdAp) which precedes the dsdA gene of E. coli (39% identity; 19 S.D.), and (iv) the gntZ gene product is homologous to 6-phosphogluconate dehydrogenases of other bacteria and of animals (48-56%; 82-178 S.D.), thereby suggesting that the B. subtilis gntZ encodes 6-phosphogluconate dehydrogenase. Several conserved regions of the sequenced 6-phosphogluconate dehydrogenases can serve as signature patterns of this protein. Computer analyses have indicated that the previously reported sequences of the porcine and ovine 6-phosphogluconate dehydrogenases, as well as the hypothetical DsdAp protein, are probably erroneous. The probable reasons for the errors are reported along with the proposed revised sequences.
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PMID:Analysis of the gluconate (gnt) operon of Bacillus subtilis. 165 48

An investigation was conducted into whether dopamine induces an alteration in the fucolysation of glycoproteins, starting from the dopamine hypothesis of schizophrenia and taking the fucokinase activity determined in erythrocytes of schizophrenic patients as parameter. As with patients with "schizoaffective psychosis" and those with manic-depressive disorders, who were likewise examined, it was found that the enzyme activity of schizophrenic patients was no different than that found in the blood of a control group.
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PMID:[Determination of fucokinase activity in the blood of schizophrenic patients]. 255 28

In slices of rat hippocampus, the influence of puromycin (0.5 mM) on dopamine (0.5 mM)-stimulated L-fucose incorporation into glycoproteins was studied. Puromycin (15 min, 2 h and 4 h pretreatment) inhibited protein synthesis by some -70% (estimated by the in vitro incorporation rate of L-leucine), whilst L-fucose incorporation into rat hippocampal glycoproteins was only inhibited about -20% (4 h pretreatment) compared to control values (100%). Under these experimental conditions, the dopamine-induced increase in both the L-fucose incorporation into glycoproteins and the activity of fucokinase was not affected by puromycin. These data suggest that these short-lasting dopamine actions do not depend on protein synthesis.
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PMID:Dopamine-stimulated fucosylation of brain proteins in vitro is not inhibited by puromycin. 298 25

Altogether 30 different sugar analogues have been tested in a cell free system from rat liver or, in part, in freshly prepared hepatocytes. It is our aim to find suitable compounds which are able either to interfere with the metabolization of L-fucose, galactose and N-acetylmannosamine or, alternatively, to block the attachment of these sugars to the nascent oligosaccharide chain. 1-Methylfucoside inhibits the fucokinase by a competitive mode (Ki = 1.1 mmol/l). Both the fucokinase and fucose-1-phosphate pyrophosphorylase activity are impaired by Clobenoside, a chloro-containing glucofuranoside (Ki values between 5 to 10 mmol/l). In hepatocytes this inhibition leads to a drastic reduction of fucoprotein biosynthesis and secretion. 1-Methylenegalactose proved to be a promising competitive inhibitor of the galactokinase (Ki = 4.1 mmol/l), while the efficacy of 2-deoxy-2-fluoro-galactose and 6-deoxy-6-fluoro-galactose is less pronounced. Part of these sugar analogues could become a suitable tool in order to elucidate the biological significance of terminal and subterminal sugars.
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PMID:Inhibitors of glycoprotein biosynthesis. 383 23


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