Stereochemical Course of the Maleate Hydratase Reaction

Englard, Sasha; Britten, John S.; Listowsky, Irving

doi:10.1016/s0021-9258(18)96042-4

Cited by 44 publications

(11 citation statements)

References 34 publications

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“…The absolute configurations of both enantiomers of monodeuterated succinate have been unequivocally determined by their synthesis from monodeuterated malate and neutron diffraction analysis . The CD spectrum of (2 S )-[2- 2 H]succinic acid shows a positive n to π* Cotton effect at 210 nm with a molar ellipticity [θ] 210 = +228° at 25 °C .…”

Section: Resultsmentioning

confidence: 99%

Stereochemical and Isotopic Labeling Studies of 2-Oxo-hept-4-ene-1,7-dioate Hydratase: Evidence for an Enzyme-Catalyzed Ketonization Step in the Hydration Reaction

Burks

Johnson

Whitman³

1998

J. Am. Chem. Soc.

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2-Oxo-hept-4-ene-1,7-dioate hydratase from Escherichia coli C converts 2-oxo-hept-4-ene-1,7-dioate to 2-oxo-4-hydroxy-hepta-1,7-dioate by the addition of water using magnesium as a cofactor. The enzyme is one of a set of inducible enzymes, known collectively as the homoprotocatechuate meta-fission pathway. The entire pathway enables the organism to utilize aromatic amino acids as its sole sources of carbon and energy. Expression and purification of 2-oxo-hept-4-ene-1,7-dioate hydratase to homogeneity permitted kinetic, isotopic labeling, and stereochemical studies. Kinetic studies show that the enzyme processes either 2-oxo-hept-4-ene-1,7-dioate or 2-hydroxy-2,4-heptadiene-1,7-dioate to product with comparable facility. Isotope labeling studies show that the hydratase catalyzes the incorporation of a solvent deuteron at both C-3 and C-5 when the reaction is performed in 2H2O. The enzyme also accelerates the exchange of the C-3 proton of the alternate substrate 2-oxo-1,7-heptadioate with solvent deuterons. The results are consistent with a mechanism in which the enzyme catalyzes the isomerization of 2-oxo-hept-4-ene-1,7-dioate to its α,β-unsaturated ketone followed by the Michael addition of water. Whether this mechanistic sequence involves a one-base or a two-base mechanism is not yet known.

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Section: Resultsmentioning

confidence: 99%

Stereochemical and Isotopic Labeling Studies of 2-Oxo-hept-4-ene-1,7-dioate Hydratase: Evidence for an Enzyme-Catalyzed Ketonization Step in the Hydration Reaction

Burks

Johnson

Whitman³

1998

J. Am. Chem. Soc.

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“…The dehydration catalyzed by maleate hydratase also takes place by an antiperiplanar elimination in which the 3- pro-R proton is removed. Scheme depicts the relative stereochemistries 3 …”

Section: E Maleate Hydratase and Dimethylmaleate Hydratasementioning

confidence: 99%

Iron−Sulfur Proteins with Nonredox Functions

1996

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“…Yorke E. Rhodes,* Victor G. DiFate Department of Chemistry, New York University University Heights, New York, New York 10453 Received June 3,1971 Optical Activity due to Isotopic Substitution. Circular Dichroism of (lR)-[2-180]-a-Fenchocamphoronequinone Sir:…”

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confidence: 99%

“…Two ORD curves only show the first half of a Cotton effect. 3 We have started the synthesis of a number of diketones which derive optical activity from substitution of one 160 by 180. The first compound which is reported here is an -diketone: (lR)-[2-180]-a-fenchocamphoronequinone (I).…”

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confidence: 99%