Mutarotation of Sugars in Solution: Part I

Pigman, Ward; Isbell, Horace S.

doi:10.1016/s0096-5332(08)60167-8

Cited by 102 publications

(63 citation statements)

References 158 publications

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“…The equilibrium Formation and Rearrangement of Aldono-1,s-lactones solution of D-galactose in pyridine at 80 "C was found by gas-liquid chromatography to contain 31.7 o/l, a-D-galactopyranose, 31.2 76 j-u-galactopyranose, 23.4 Pa-galactofuranose, and 13.7 :{ a-D-galactofuranose [46]. Such a distribution of the isomers of D-galaCtoSe, with its significant decrease of p-Dpyranose content as compared with the aqueous equilibrium, should be accessible to enzymatic analysis, even if the interconversion of furanose to pyranose forms would be as fast as, or faster than, the pyranose to furanose interconversion [47,48].…”

Section: Emsmentioning

confidence: 99%

Reaction Mechanism of d-Galactose Dehydrogenases from Pseudomonas saccharophila and Pseudomonas fluorescens. Formation and Rearrangement of Aldono-1,5-lactones

1974

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1. b-D-Galactopyranose has been shown by specificity studies and by gas-liquid chromatographic investigations to be the substrate of the D-galactose dehydrogenases from Pseudomonas sacchurophilu and from Pseudomonas fluorescens.2. cc-~-Galactopyranose and the two ring-isomeric D-galactofuranoses are oxidized, at high enzyme concentrations, only after their rate-limiting isomerization into the b-D-pyranose. The open-chained aldehyde form of D-galactose has been likewise excluded as substrate.3. D-Galactono-l,5-lactone has been shown by gas-liquid chromatography to be the immediate product of the enzymatic dehydrogenation of D-galactose and identified by combined gas-liquid chromatography -mass spectrometry of the isolated trimethylsilylated derivative.4. The primarily formed D-galactono-l,5-lactone rearranges non-enzymatically to the corresponding D-galactono-l,4-lactone by an intramolecular rearrangement without the participation of the open-chained D-galactonate. This rearrangement is strongly dependent on the pH-value, having a first-order rate constant k = 1.0 min-' at pH 6.8 under the conditions used. were determined at pH 6.8 under the conditions used, enabling the estimation of the apparent equilibrium constant for the reaction catalyzed by the enzyme6. Results analogous to those with D-galactose were obtained from investigations with the homeomorphic L-arabinose. The pyranose ring with the hydroxyl group at carbon-1 in the equatorial position is likewise the only substrate, and the immediate product, the 1,5-lactone, also rearranges subsequently to the corresponding 1,4-lactone, having a first-order rate constant k = 0.22 min-l at pH 6.8 under the conditions used. The ~-arabinono-1,5-lactone has also been identified by gas-liquid chromatography -mass spectrometry of the trimethylsilylated derivative.

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Section: Emsmentioning

confidence: 99%

Reaction Mechanism of d-Galactose Dehydrogenases from Pseudomonas saccharophila and Pseudomonas fluorescens. Formation and Rearrangement of Aldono-1,5-lactones

1974

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“…That this cyclic oxocarbenium ion was found in the present study for 1 and not for 2 may be of relevance as regards both the rates of mutarotation of 1 and 2 and the rates of acid-catalyzed hydrolysis of the corresponding glycosides. It is well known that 1 exhibits rapid mutarotation while 2 does not (27), and that methyl P-D-fructopyranoside is hydrolyzed at a significantly faster rate than is methyl a-L-sorbopyranoside (28,29). The implications of these calculations, as concerns the mechanisms of mutarotation of ketopyranoses and of ketopyranoside hydrolysis, will be the subject of a future study.…”

Section: Proton Af/initiesmentioning

confidence: 95%

The proton affinities and deprotonation enthalpies of β-D-fructopyranose and α-L-sorbopyranose

Woods¹,

Szarek²,

Smith³

1991

Can. J. Chem.

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The proton affinities (PAS) and deprotonation enthalpies (DPEs) were calculated for the pyranoid forms of two naturally occumng sugars, D-fructose and L-sorbose. In both molecules the PAS of the primary hydroxyl group (HO-1), the anomeric hydroxyl group (HO-2), and the ring-oxygen atom (0-6) were calculated, as were the DPEs of HO-1 and HO-2. The stabilities of the conjugate acids and bases of these sugars are enhanced by the presence of intramolecular hydrogen bonding, a feature that is significant in explaining the differences in sweetness and the rates of mutarotation of the title compounds, as well as the differences in the rates of acid-catalyzed hydrolysis of ketopyranosides.Key words: proton affinity, deprotonation enthalpy, ab initio calculations, AMl, hexuloses. IntroductionThe most direct computational approach to the measurement of atomic and molecular acidities and basicities is through evaluation of the deprotonation enthalpies (DPEs) and proton affinities (PAS) of the acids and bases, respectively. Ab initio computational methods are well suited for the evaluation of the PAS and DPEs of small molecules, and have been employed extensively for such calculations (1). Del Bene (2) has reported the effects of basis set choice and electron correlation on ab initio calculations of the PAS of several oxygen and nitrogen bases, consisting of compounds containing no more than two non-hydrogen atoms. The most accurate results reported by her were within 1-3 kcal/mol of the experimental values, and were obtained from calculations employing a triple-split valence basis set (6-311G) with two sets of polarization functions and one set of diffuse functions on all non-hydrogen atoms, and one set of polarization functions on the hydrogen atoms. It should be noted that it has been recently reported (3) that the 6-3 11G basis

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“…This reaction differs from others discussed in that the asymmetry of C-1 of sugars is based on the establishment of the hemiacetal linkage on cyclization; and "racemization" at C-1 is effected by way of an aldehyde intermediate, consequent to cleaving the hemiacetal carbon-oxygen bond. Nonenzymatic mutarotation of sugars has been rather extensively studied and was recently reviewed (81,82). Enzymatic mutarotation of glucose was first detected as a reaction catalyzed by a preparation of Penicillium D-glucose oxidase (83); subsequently, a mutarotase, so named, was separated from the oxidase (84).…”

Section: Mutarotases (Aldose-1-epimerases)mentioning

confidence: 99%

Catalytic Aspects of Enzymatic Racemization

Adams

1976

Advances in Enzymology - And Related Areas of Molecular Biology

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Mutarotation of Sugars in Solution: Part I

Cited by 102 publications

References 158 publications

Reaction Mechanism of d-Galactose Dehydrogenases from Pseudomonas saccharophila and Pseudomonas fluorescens. Formation and Rearrangement of Aldono-1,5-lactones

Reaction Mechanism of d-Galactose Dehydrogenases from Pseudomonas saccharophila and Pseudomonas fluorescens. Formation and Rearrangement of Aldono-1,5-lactones

The proton affinities and deprotonation enthalpies of β-D-fructopyranose and α-L-sorbopyranose

Catalytic Aspects of Enzymatic Racemization

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