Anomalous mutarotation of glucose 6-phosphate. An example of intramolecular catalysis

Bailey, J. Martyn; Fishman, Peter H.; Pentchev, Peter G.

doi:10.1021/bi00807a020

Cited by 53 publications

(45 citation statements)

References 6 publications

(10 reference statements)

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“…No //-glucose-6-phosphate was, however, found in the reaction mixture to which 200 pi of 4 mol/1 perchloric acid was added to stop the reaction. This result shows that a-D-glucose-6-phosphate formed in the reaction mixture was also estimated as ß-Z>-glucose-6-phosphate under our experimental con ditions because of rapid mutarotation between a-and ß-Z/-glucose-6-phosphate [17],…”

Section: Hexokinase Assaysupporting

confidence: 67%

D-Glucose Anomeric Preference of Hexokinases from Animals and Yeast

Okuda¹,

Miwa²,

Inagaki³

1984

Enzyme

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The D-glucose anomeric preference of hexokinases partially purified from animals (rat, mouse, and chicken) and baker’s yeast (Saccharomyces cerevisiae) were investigated by the assay system with glucose-6-phosphate dehydrogenase as a coupling enzyme. With low K(m) hexokinases in animal tissues and cells, the ratios of Vmax for the ß-anomer to Vmax for the α-anomer (V(ß)/V(α)) were within a range from 1.3 to 1.5. In yeast, the V(ß)/V(α) value was 1.1 for hexokinase A, 0.8 for hexokinase B, and 1.4 for glucokinase. The possible explanation for D-glucose anomeric preference of hexokinase is discussed.

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Section: Hexokinase Assaysupporting

confidence: 67%

D-Glucose Anomeric Preference of Hexokinases from Animals and Yeast

Okuda¹,

Miwa²,

Inagaki³

1984

Enzyme

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“…Because of the specificity of glucose-6-phosphate dehydrogenase for/3-G6P [ 1, 10-13 ] the spontaneous and enzyme catalysed formation of/3-G6P from c~-G6P can be tested in the following systems with G6PDH as indicator-enzyme [1,3,10,11,14]: The system is started by addition of freshly dissolved a-D-glucopyranose. As soon as the steady state is reached, after reaction time of 1 min [14], the reactions are quenched by addition of 0.…”

Section: Test Systemsmentioning

confidence: 99%

Glucose‐6‐phosphate‐1‐epimerase from baker's yeast. A new enzyme

Wurster

Hess

1972

FEBS Letters

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“…Phosphoglucomutases catalyze the interconversion of D-glucose 1-phosphate (G1P) 1 and D-glucose 6-phosphate (G6P). Operating in the forward G6P-forming direction, this reaction links polysaccharide phosphorolysis to glycolysis.…”

mentioning

confidence: 99%

Conformational Cycling in β-Phosphoglucomutase Catalysis: Reorientation of the β-d-Glucose 1,6-(Bis)phosphate Intermediate

et al. 2006

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Activated Lactococcus lactis -phosphoglucomutase ( PGM) catalyzes the conversion of -Dglucose 1-phosphate ( G1P) derived from maltose to -D-glucose 6-phosphate (G6P). Activation requires Mg 2+ binding and phosphorylation of the active site residue Asp8. Initial velocity techniques were used to define the steady-state kinetic constants k cat ) 177 ( 9 s -1 , K m ) 49 ( 4 µM for the substrate G1P and K m ) 6.5 ( 0.7 µM for the activator -D-glucose 1,6-bisphosphate ( G1,6bisP). The observed transient accumulation of [ 14 C] G1,6bisP (12% at ∼0.1 s) in the single turnover reaction carried out with excess PGM (40 µM) and limiting [ 14 C] G1P (5 µM) and G1,6bisP (5 µM) supported the role of G1,6bisP as a reaction intermediate in the conversion of the G1P to G6P. Single turnover reactions of [ 14 C] G1,-6bisP with excess PGM were carried out to demonstrate that phosphoryl transfer rather than ligand binding is rate-limiting and to show that the G1,6bisP binds to the active site in two different orientations (one positioning the C(1)phosphoryl group for reaction with Asp8, and the other orientation positioning the C(6)phosphoryl group for reaction with Asp8) with roughly the same efficiency. Single turnover reactions carried out with PGM, [ 14 C] G1P, and unlabeled G1,6bisP demonstrated complete exchange of label to the G1,6bisP during the catalytic cycle. Thus, the reorientation of the G1,6bisP intermediate that is required to complete the catalytic cycle occurs by diffusion into solvent followed by binding in the opposite orientation. Published X-ray structures of G1P suggest that the reorientation and phosphoryl transfer from G1,6bisP occur by conformational cycling of the enzyme between the active site open and closed forms via cap domain movement. Last, the equilibrium ratio of G1,6bisP to G1P plus G6P was examined to evidence a significant stabilization of PGM aspartyl phosphate.Phosphoglucomutases catalyze the interconversion of D-glucose 1-phosphate (G1P) 1 and D-glucose 6-phosphate (G6P). Operating in the forward G6P-forming direction, this reaction links polysaccharide phosphorolysis to glycolysis. In the reverse direction, the reaction provides G1P for the biosynthesis of exo-polysaccharides (2). There are two classes of phosphoglucomutases, the R-phosphoglucomutases (RPGM, EC 5.4.2.2), ubiquitous among eucaryotes and procaryotes, and the -phosphoglucomutases ( PGM, EC 5.4.2.6), present in certain bacteria and protists. The two classes of mutases are distinguished by their specificity for R-and -D-glucose phosphates and by their protein-fold family. The rabbit muscle RPGM (3) and the closely related Pseudomonas aeruginosa RPGM/RPMM (4) are members of the phosphohexomutase enzyme superfamily (5), whereas PGM (6) belongs to the haloalkanoic acid (HAD) enzyme superfamily (7). The four-domain RPGM and RPGM/RPMM (∼50 kDa) are approximately twice the size of the twodomain PGM (∼25 kDa).In RPGM (and in RPGM/RPMM), phosphoryl transfer is mediated by an active site serine which forms a stable phosphate ester...

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Anomalous mutarotation of glucose 6-phosphate. An example of intramolecular catalysis

Cited by 53 publications

References 6 publications

D-Glucose Anomeric Preference of Hexokinases from Animals and Yeast

D-Glucose Anomeric Preference of Hexokinases from Animals and Yeast

Glucose‐6‐phosphate‐1‐epimerase from baker's yeast. A new enzyme

Conformational Cycling in β-Phosphoglucomutase Catalysis: Reorientation of the β-d-Glucose 1,6-(Bis)phosphate Intermediate

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