Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methylation of glucosamine-6-phosphate isomerase deaminase (2-amino-2-deoxy-D-glucose-6-phosphate ketol-isomerase, deaminating, or glucosamine-6-phosphate deaminase, EC 5.3.1.10), from Escherichia coli produces a modified protein having two alkylated sulfhydryls per each polypeptide chain. The enzyme is still active and allosteric, but exhibits a lower homotropic cooperativity and its Vmax/Etotal is almost exactly half that of the native enzyme. Arsenite produces comparable kinetic changes that can be reversed with ethanedithiol but not with 2-thioethanol or dialysis. Thiols can be oxidized by molecular oxygen using the (1,10-phenanthroline)3-Cu(II) complex as catalyst; the enzyme obtained no longer has titrable SH groups with 5,5'-dithiobis(2-nitrobenzoic acid) and displays kinetic behavior similar to that of the other chemically modified forms of the deaminase using monofunctional or bifunctional reagents. The results reported indicate that the involved sulfhydryls are vicinal groups, and are located in a region of the molecule that moves as a whole in the allosteric transition.
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PMID:Evidence for vicinal thiols and their functional role in glucosamine-6-phosphate deaminase from Escherichia coli. 264 29

1. Growth of Escherichia coli on glucosamine results in an induction of glucosamine 6-phosphate deaminase [2-amino-2-deoxy-d-glucose 6-phosphate ketol-isomerase (deaminating), EC 5.3.1.10] and a repression of glucosamine 6-phosphate synthetase (l-glutamine-d-fructose 6-phosphate aminotransferase, EC 2.6.1.16); glucose abolishes these control effects. 2. Growth of E. coli on N-acetylglucosamine results in an induction of N-acetylglucosamine 6-phosphate deacetylase and glucosamine 6-phosphate deaminase, and in a repression of glucosamine 6-phosphate synthetase; glucose diminishes these control effects. 3. The synthesis of amino sugar kinases (EC 2.7.1.8 and 2.7.1.9) is unaffected by growth on amino sugars. 4. Glucosamine 6-phosphate synthetase is inhibited by glucosamine 6-phosphate. 5. Mutants of E. coli that are unable to grow on N-acetylglucosamine have been isolated, and lack either N-acetylglucosamine 6-phosphate deacetylase (deacetylaseless) or glucosamine 6-phosphate deaminase (deaminaseless). Deacetylaseless mutants can grow on glucosamine but deaminaseless mutants cannot. 6. After growth on glucose, deacetylaseless mutants have a repressed glucosamine 6-phosphate synthetase and a super-induced glucosamine 6-phosphate deaminase; this may be related to an intracellular accumulation of acetylamino sugar that also occurs under these conditions. In one mutant the acetylamino sugar was shown to be partly as N-acetylglucosamine 6-phosphate. Deaminaseless mutants have no abnormal control effects after growth on glucose. 7. Addition of N-acetylglucosamine or glucosamine to cultures of a deaminaseless mutant caused inhibition of growth. Addition of N-acetylglucosamine to cultures of a deacetylaseless mutant caused lysis, and secondary mutants were isolated that did not lyse; most of these secondary mutants had lost glucosamine 6-phosphate deaminase and an uptake mechanism for N-acetylglucosamine. 8. Similar amounts of (14)C were incorporated from [1-(14)C]-glucosamine by cells of mutants and wild-type growing on broth. Cells of wild-type and a deaminaseless mutant incorporated (14)C from N-acetyl[1-(14)C]glucosamine more efficiently than from N[1-(14)C]-acetylglucosamine, incorporation from the latter being further decreased by acetate; cells of a deacetylaseless mutant showed a poor incorporation of both types of labelled N-acetylglucosamine.
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PMID:Control of amino sugar metabolism in Escherichia coli and isolation of mutants unable to degrade amino sugars. 486 32

Flavobacterium glycosylasparaginase was cloned in an Escherichia coli expression system. Site-directed mutagenesis was performed at residues suggested to be important in the catalytic mechanism based on the crystal structure of the human enzyme and other biochemical studies. In vitro autoproteolysis allowed the mutant enzymes to be activated, including those that were slow to self-cleave. Based on the activity of the mutant enzymes, six catalytically essential amino acids were identified: Trp-11, Asp-66, Thr-152, Thr-170, Arg-180, and Asp-183. Kinetic analysis of each mutant further defined the function of these residues in substrate specificity and reaction rate. Mutagenesis of the N-terminal nucleophile residue Thr-152 confirmed the key function of its side-chain hydroxyl group. Partial activities of mutants T152S/C were in agreement with the general mechanism of N-terminal nucleophile (Ntn)-amidohydrolases. The side-chain hydroxyl of Thr-170 contributes to the reaction rate based on studies of mutants T170S/C/A. Residues Asp-183 and Arg-180 were found to H-bond, respectively, with the charged alpha-amino and alpha-carboxyl group of the substrate (Asn-GlcNAc). Mutants R180Q/L and D183E/N had greatly decreased substrate affinity and reduced reaction rates. Kinetic studies also showed that Trp-11 is involved in regulation of the enzyme reaction rate, contradictory to a previous suggestion that this residue is involved in substrate binding. Asp-66 is a new residue found to be important in enzyme activity. The overall active site structure involving these catalytic residues resembles the glutaminase domain of glucosamine 6-phosphate synthase, another member of the Ntn-amidohydrolase family of enzymes.
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PMID:Site-directed mutagenesis of essential residues involved in the mechanism of bacterial glycosylasparaginase. 954 3

Glucosamine-6P-deaminase (EC 3.5.99.6, formerly glucosamine-6-phosphate isomerase, EC 5.3.1.10) from Escherichia coli is an attractive experimental model for the study of allosteric transitions because it is both kinetically and structurally well-known, and follows rapid equilibrium random kinetics, so that the kinetic K(m) values are true thermodynamic equilibrium constants. The enzyme is a typical allosteric K-system activated by N-acetylglucosamine 6-P and displays an allosteric behavior that can be well described by the Monod-Wyman-Changeux model. This thermodynamic study based on the temperature dependence of allosteric parameters derived from this model shows that substrate binding and allosteric transition are both entropy-driven processes in E. coli GlcN6P deaminase. The analysis of this result in the light of the crystallographic structure of the enzyme implicates the active-site lid as the structural motif that could contribute significantly to this entropic component of the allosteric transition because of the remarkable change in its crystallographic B factors.
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PMID:Allosteric transition and substrate binding are entropy-driven in glucosamine-6-phosphate deaminase from Escherichia coli. 1159 28

The enzyme, glucosamine-6-phosphate isomerase (GNPI) or deaminase (GNPDA) (EC 5.3.1.10), catalyzes the conversion of GNP to fructose-6-phosphate and ammonia, with an aldo/keto isomerization and an amination/deamination. A hamster sperm-derived protein (Oscillin) with high similarity to bacterial GNPI has been proved to be capable of inducing calcium oscillation in eggs at fertilization. GNPI/Oscillin was supposed to be an important factor in starting embryonic development. From the cDNA library of human dendritic cells (DC), we isolated a novel full-length cDNA encoding a 276-amino acid-residue protein that shares high homology with human GNPI/Oscillin. So, the novel molecule is named as GNPI2. The GNPI2 gene consists of seven exons and six introns. It is mapped to chromosome 4. Northern blot analysis indicated that the tissue distribution of GNPI2 mRNA is different from that of human GNPI or Oscillin mRNA. GNPI2 is ubiquitously expressed in most of human tissues with high expression in testis, ovary, placenta, and heart. Like GNPI, the recombinant GNPI2 has been proved to have the enzymatic activity to catalyze the conversion of GNP to fructose-6-phosphate. Our results indicated that GNPI2 is a novel protein with definite function as a GNPI.
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PMID:Cloning and functional characterization of GNPI2, a novel human homolog of glucosamine-6-phosphate isomerase/oscillin. 1261 32

1. Glucosamine 6-phosphate deaminase [2-amino-2-deoxy-d-glucose 6-phosphate ketol-isomerase (deaminating), EC 5.3.1.10] of Bacillus subtilis has been partially purified. Its K(m) is 3.0mm. 2. Extracts of B. subtilis contain N-acetylglucosamine 6-phosphate deacetylase (K(m) 1.4mm), glucosamine 1-phosphate acetylase and amino sugar kinases (EC 2.7.1.8 and 2.7.1.9). 3. Glucosamine 6-phosphate synthetase (l-glutamine-d-fructose 6-phosphate aminotransferase, EC 2.6.1.16) is repressed by growth of B. subtilis in the presence of glucosamine, N-acetylglucosamine, N-propionylglucosamine or N-formylglucosamine. Glucosamine 6-phosphate deaminase and N-acetylglucosamine 6-phosphate deacetylase are induced by N-acetylglucosamine. Amino sugar kinases are induced by glucose, glucosamine and N-acetylglucosamine. The synthesis of glucosamine 1-phosphate acetylase is unaffected by amino sugars. 4. Glucose in the growth medium prevents the induction of glucosamine 6-phosphate deaminase and of N-acetylglucosamine 6-phosphate deacetylase caused by N-acetylglucosamine; glucose also alleviates the repression of glucosamine 6-phosphate synthetase caused by amino sugars. 5. Glucosamine 6-phosphate deaminase increases in bacteria incubated beyond the exponential phase of growth. This increase is prevented by glucose.
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PMID:FURTHER STUDIES ON THE REGULATION OF AMINO SUGAR METABOLISM IN BACILLUS SUBTILIS. 1434 23

A key step in amino sugar metabolism is the interconversion between fructose-6-phosphate (Fru6P) and glucosamine-6-phosphate (GlcN6P). This conversion is catalyzed in the catabolic and anabolic directions by GlcN6P deaminase and GlcN6P synthase, respectively, two enzymes that show no relationship with one another in terms of primary structure. In this study, we examined the catalytic properties and regulatory features of the glmD gene product (GlmD(Tk)) present within a chitin degradation gene cluster in the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1. Although the protein GlmD(Tk) was predicted as a probable sugar isomerase related to the C-terminal sugar isomerase domain of GlcN6P synthase, the recombinant GlmD(Tk) clearly exhibited GlcN6P deaminase activity, generating Fru6P and ammonia from GlcN6P. This enzyme also catalyzed the reverse reaction, the ammonia-dependent amination/isomerization of Fru6P to GlcN6P, whereas no GlcN6P synthase activity dependent on glutamine was observed. Kinetic analyses clarified the preference of this enzyme for the deaminase reaction rather than the reverse one, consistent with the catabolic function of GlmD(Tk). In T. kodakaraensis cells, glmD(Tk) was polycistronically transcribed together with upstream genes encoding an ABC transporter and a downstream exo-beta-glucosaminidase gene (glmA(Tk)) within the gene cluster, and their expression was induced by the chitin degradation intermediate, diacetylchitobiose. The results presented here indicate that GlmD(Tk) is actually a GlcN6P deaminase functioning in the entry of chitin-derived monosaccharides to glycolysis in this hyperthermophile. This enzyme is the first example of an archaeal GlcN6P deaminase and is a structurally novel type distinct from any previously known GlcN6P deaminase.
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PMID:Characterization of a novel glucosamine-6-phosphate deaminase from a hyperthermophilic archaeon. 1619 74