GMP reductase in Artemia salina

Renart, Margarita F.; Sillero, Antonio

doi:10.1016/0005-2744(74)90078-3

Cited by 21 publications

(11 citation statements)

References 8 publications

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“…ITC data were fitted to eqn (8), where DH is the enthalpy of process given by the ITC experiment, DG is the Gibbs free energy changes, DS is the entropy changes, T is the temperature of the experiment in Kelvin, R is the gas constant (1.987 cal K À1 mol -1 ), and K eq is the equilibrium binding constant. The dissociation constant, K d , is the inverse of the equilibrium binding constant, K eq , described in eqn (9).…”

Section: Discussionmentioning

confidence: 99%

“…7 In purine auxotroph mutants that are blocked prior to the formation of IMP, guaC mutations prevent the use of Gua or xanthine derivatives as sources of purine. 3 GMP reductases have been found and characterized in a number of organisms, including E. coli, 3 Salmonella typhimurium, 6 Artemia salina, 8 Leishmania donovani, 9 and Homo sapiens. 10 The human homologue is responsible for the only known metabolic step by which Gua nucleotides can be converted to the pivotal precursor of both Ade and Gua nucleotides.…”

Section: Introductionmentioning

confidence: 99%

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Recombinant Escherichia coli GMP reductase: kinetic, catalytic and chemical mechanisms, and thermodynamics of enzyme–ligand binary complex formation

et al. 2011

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Guanosine monophosphate (GMP) reductase catalyzes the reductive deamination of GMP to inosine monophosphate (IMP). GMP reductase plays an important role in the conversion of nucleoside and nucleotide derivatives of guanine to adenine nucleotides. In addition, as a member of the purine salvage pathway, it also participates in the reutilization of free intracellular bases. Here we present cloning, expression and purification of Escherichia coli guaC-encoded GMP reductase to determine its kinetic mechanism, as well as chemical and thermodynamic features of this reaction. Initial velocity studies and isothermal titration calorimetry demonstrated that GMP reductase follows an ordered bi-bi kinetic mechanism, in which GMP binds first to the enzyme followed by NADPH binding, and NADP(+) dissociates first followed by IMP release. The isothermal titration calorimetry also showed that GMP and IMP binding are thermodynamically favorable processes. The pH-rate profiles showed groups with apparent pK values of 6.6 and 9.6 involved in catalysis, and pK values of 7.1 and 8.6 important to GMP binding, and a pK value of 6.2 important for NADPH binding. Primary deuterium kinetic isotope effects demonstrated that hydride transfer contributes to the rate-limiting step, whereas solvent kinetic isotope effects arise from a single protonic site that plays a modest role in catalysis. Multiple isotope effects suggest that protonation and hydride transfer steps take place in the same transition state, lending support to a concerted mechanism. Pre-steady-state kinetic data suggest that product release does not contribute to the rate-limiting step of the reaction catalyzed by E. coli GMP reductase.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Recombinant Escherichia coli GMP reductase: kinetic, catalytic and chemical mechanisms, and thermodynamics of enzyme–ligand binary complex formation

et al. 2011

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“…GMP reductase has been purified from several sources, e.g. calf thymus (Stephens & Whittaker, 1973), human erythrocytes (Spector et al, 1979), Artemia salina (Renart & Sillero, 1974), Leishmania donovani (Spector & Jones, 1982), as well as from Escherichia coli and Salmonella typhimurium (Mager & Magasanik, 1960;Neuhard & Nygaard, 1987). The bacterial enzymes are strongly inhibited by ATP and reactivated by GTP and the S. typhimurium enzyme is reported to be a tetramer of identical 45 kDa subunits (Neuhard & Nygaard, 1987).…”

Section: Introductionmentioning

confidence: 99%

Nucleotide sequence of the gene encoding the GMP reductase of Escherichia coli K12

Andrews

Guest

1988

Biochemical Journal

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(1) The nucleotide sequence of a 1991 bp segment of DNA that expresses the GMP reductase (guaC) gene of Escherichia coli K12 was determined. (2) This gene comprises 1038 bp, 346 codons (including the initiation codon but excluding the termination codon), and it encodes a polypeptide of Mr 37,437 which is in good agreement with previous maxicell studies. (3) The sequence contains a putative promoter 102 bp upstream of the translational start codon, and this is immediately followed by a (G + C)-rich discriminator sequence suggesting that guaC expression may be under stringent control (4) The GMP reductase exhibits a high degree of sequence identity (34%) with IMP dehydrogenase (the guaB gene product) indicative of a close evolutionary relationship between the salvage pathway and the biosynthetic enzymes, GMP reductase and IMP dehydrogenase, respectively. (5) A single conserved cysteine residue, possibly involved in IMP binding to IMP dehydrogenase, was located within a region that possesses some of the features of a nucleotide binding site. (6) The IMP dehydrogenase polypeptide contains an internal segment of 123 amino acid residues that has no counterpart in GMP reductase and may represent an independent folding domain flanked by (alanine + glycine)-rich interdomain linkers.

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“…The utilization of GppppG may therefore control the onset of DNA synthesis in developing Artemia. (76).…”

Section: Diguanosine Tetraphosphate [G(59pppp(5j)g] and Related Strucmentioning

confidence: 99%

The search for guanosine tetraphosphate (ppGpp) and other unusual nucleotides in eucaryotes.

Silverman¹,

Atherly²

1979

Microbiological Reviews

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GMP reductase in Artemia salina

Cited by 21 publications

References 8 publications

Recombinant Escherichia coli GMP reductase: kinetic, catalytic and chemical mechanisms, and thermodynamics of enzyme–ligand binary complex formation

Recombinant Escherichia coli GMP reductase: kinetic, catalytic and chemical mechanisms, and thermodynamics of enzyme–ligand binary complex formation

Nucleotide sequence of the gene encoding the GMP reductase of Escherichia coli K12

The search for guanosine tetraphosphate (ppGpp) and other unusual nucleotides in eucaryotes.

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