Protolytic Cleavage of Vinyl Ethers. General Acid Catalysis, Structural Effects and Deuterium Solvent Isotope Effects.

Salomaa, Pentti; Kankaanperä, Alpo; Lajunen, Martti; Wagnières, Marc; Williams, D. H.; Bunnenberg, E.; Djerassi, Carl; Records, Ruth

doi:10.3891/acta.chem.scand.20-1790

Cited by 51 publications

(22 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Lehmann & Schroter (1972) reported that glycals carrying a reactive enol ether bond that is readily protonated by general acid catalysis (Salomaa et al, 1966) are utilized by glycosidases, yielding an incipient glucosyl residue. Subsequently, The product formed by a-glucan phosphorylases from D-glucal in D20 is 2-deoxy-a-D-[2(e)-* 2H]glucose oligo-or polysaccharide (Figures 6 and 7) with the deuterium atom and the saccharide acceptor in cis configuration.…”

Section: Discussionmentioning

confidence: 99%

General acid base catalysis of .alpha.-glucan phosphorylases: stereospecific glucosyl transfer from D-glucal is a pyridoxal 5'-phosphate and orthophosphate (arsenate) dependent reaction

Klein¹,

Palm²,

Helmreich³

1982

Biochemistry

View full text Add to dashboard Cite

D-Glucal, containing a highly reactive double bond, can replace glucose 1-phosphate as the glucosyl donor in phosphorylase-catalyzed glucosyl transfer to a suitable oligo- or polysaccharide acceptor: D-glucal + Pi + (glucose)Pi leads to n 2-deoxy-alpha-D-glucosyl(glucose)n in equilibrium 2-deoxy-alpha-D-glucose-1-P + (glucose)n. This reaction is catalyzed by alpha-glucan phosphorylases from rabbit skeletal muscle, potato tuber, and Escherichia coli. D-Glucal is only measurably consumed by alpha-glucan phosphorylases when orthophosphate or arsenate is present. With saturating concentrations of these anions and a glucosyl acceptor, the D-glucal reaction proceeds at rates comparable with the rates of glucosyl transfer from glucose 1-phosphate and of phosphorolysis or arsenolysis of poly- or oligosaccharides. Furthermore, for the reaction to proceed, the enzyme must be in the active conformation containing the cofactor pyridoxal 5'-phosphate in its dianionic form. On the basis of proton nuclear magnetic resonance spectra, it is proposed that protonation at C-2 of D-glucal gives rise to a hypothetical 2-deoxy-beta-D-glucose intermediate, yielding as a final product (2-deoxy-alpha-D-[2(e)-2H]glucose)n alpha (1 leads to 4) saccharides. These 2-deoxy-alpha-D-glucose oligo- or polysaccharides are degraded by alpha-glucan phosphorylases by phosphorolysis or arsenolysis like natural linear and branched alpha-glucans. The absolute requirement of the D-glucal reaction for phosphate (or arsenate) and its dependency on the dianionic form of the pyridoxal 5'-phosphate bound to phosphorylase are rationalized in terms of a proton transfer relay involving juxtaposed phosphates. Phosphate--phosphate interactions were postulated by Withers et al. [Withers, S. G., Madsen, N. B., Sykes, B. D., Takagi, M., Shimomura, S., & Fukui, T. (1981) J. Biol. Chem. 256, 10759-10762].

show abstract

Section: Discussionmentioning

confidence: 99%

General acid base catalysis of .alpha.-glucan phosphorylases: stereospecific glucosyl transfer from D-glucal is a pyridoxal 5'-phosphate and orthophosphate (arsenate) dependent reaction

Klein¹,

Palm²,

Helmreich³

1982

Biochemistry

View full text Add to dashboard Cite

show abstract

“…We will use the set of reactions shown in scheme 2. The rate constant for protonation of 2-methoxypropene is known, 970 M -I s-' (26). The equilibrium constant for oxocation formation from 2,2-dimethoxypropane can be calculated from the rate constant for hydrolysis of acetone dimethyl acetal, 2950 M-' s-I,' and the rate constant for trapping of the cation by methanol, 1.08 X lo6 M-' s-I, (27), as 0.0027.…”

Section: Exchange Datamentioning

confidence: 99%

Energetics of acetic acid enol in aqueous solution. A new method for thermodynamic estimation

Guthrie¹

1993

Can. J. Chem.

View full text Add to dashboard Cite

A new disproportionation cal'culation allows the estimation of the free energy of formation of the en01 of acetic acid as 65 k 2 kcal/mol. The value of pK, derived from this free energy, pKE = 21 * 2, is in satisfactory agreement with information from the literature about rates of exchange. Analysis of the data on rates of exchange of the C-H protons of acetic acid using Marcus theory allows an independent estimate of the en01 content. Exchange in acid and in base lead to internally consistent estimates, pKE = 19.3 k 2.2, which are within the combined uncertainties of the values from the thermodynamic estimate.

show abstract

“…8 In all these cases the conversion of ethylene to products at equilibrium was very high (>95%). [6][7][8] It has been proposed in an excellent recent textbook9 that isobutene "undoubtedly" hydrates via protonation on carbon to give the iert-butyl cation (eq 2) h+ h2o…”

mentioning

confidence: 99%

Reactivity of cyclic and acyclic olefinic hydrocarbons in acid-catalyzed hydration

Chwang¹,

Nowlan²,

Tidwell³

1977

J. Am. Chem. Soc.

View full text Add to dashboard Cite

Protolytic Cleavage of Vinyl Ethers. General Acid Catalysis, Structural Effects and Deuterium Solvent Isotope Effects.

Cited by 51 publications

References 0 publications

General acid base catalysis of .alpha.-glucan phosphorylases: stereospecific glucosyl transfer from D-glucal is a pyridoxal 5'-phosphate and orthophosphate (arsenate) dependent reaction

General acid base catalysis of .alpha.-glucan phosphorylases: stereospecific glucosyl transfer from D-glucal is a pyridoxal 5'-phosphate and orthophosphate (arsenate) dependent reaction

Energetics of acetic acid enol in aqueous solution. A new method for thermodynamic estimation

Reactivity of cyclic and acyclic olefinic hydrocarbons in acid-catalyzed hydration

Contact Info

Product

Resources

About