996. Kinetics of hydration of aliphatic aldehydes

Gruen, L.C.; McTigue, PT

doi:10.1039/jr9630005224

Cited by 22 publications

(11 citation statements)

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“…Since the carbonyl form of an aldehyde is more volatile than the gem -diol, it is reasonable to expect that most of an aldehyde sample reaching the nose through the air will initially be in the carbonyl form. Aldehydes undergo rapid acid- 25 and base- 44 catalyzed hydration, but at the slightly acidic pH of the nasal epithelium, 45 the uncatalyzed rate of hydration is expected to be slow ( k ≈ 3.5 × 10 –3 s –1 , t 1/2 = 3.3 min). 25 Although some gem -diol will have formed within the time it takes to perceive an aldehyde, without catalysis the equilibrium concentration will not be achieved within that time.…”

Section: Resultsmentioning

confidence: 99%

Aldehyde Recognition and Discrimination by Mammalian Odorant Receptors via Functional Group-Specific Hydration Chemistry

Peterlin

et al. 2014

ACS Chem. Biol.

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The mammalian odorant receptors (ORs) form a chemical-detecting interface between the atmosphere and the nervous system. This large gene family is composed of hundreds of membrane proteins predicted to form as many unique small molecule binding niches within their G-protein coupled receptor (GPCR) framework, but very little is known about the molecular recognition strategies they use to bind and discriminate between small molecule odorants. Using rationally designed synthetic analogs of a typical aliphatic aldehyde, we report evidence that among the ORs showing specificity for the aldehyde functional group, a significant percentage detect the aldehyde through its ability to react with water to form a 1,1-geminal (gem)-diol. Evidence is presented indicating that the rat OR-I7, an often-studied and modeled OR known to require the aldehyde function of octanal for activation, is likely one of the gem-diol activated receptors. A homology model based on an activated GPCR X-ray structure provides a structural hypothesis for activation of OR-I7 by the gem-diol of octanal.

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Section: Resultsmentioning

confidence: 99%

Aldehyde Recognition and Discrimination by Mammalian Odorant Receptors via Functional Group-Specific Hydration Chemistry

Peterlin

et al. 2014

ACS Chem. Biol.

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“…Values for D-glyceraldehyde (Angyal & Wheen, 1980) and other aldehydes and ketones (Lewis & Wolfenden, 1977) have been obtained by similar NMR techniques. To obtain the equilibrium constant in H20, the [hydrate]/[aldehyde] ratio in D 2 0 was multiplied by 0.84 to correct for the solvent deuterium isotope effect on the hydration equilibrium (Gruen & McTigue, 1963); the results are reported in Table I. l80 Transfer from Hydrate to Phosphate. In these experiments, the enzymatic ATPase activity competes with the nonenzymatic washout of l 8 0 from the aldehyde and hydrate.…”

Section: Methodsmentioning

confidence: 99%

A novel method for determining rate constants for dehydration of aldehyde hydrates

Rendina¹,

Hermes²,

Cleland³

1984

Biochemistry

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A method has been developed for calculating rate constants for dehydration of aldehydes that induce ATPase reactions by kinases and where 18O is transferred from the aldehyde or its hydrate to inorganic phosphate during the reaction. The method involves measurement of the fraction of 18O in phosphate by 31P NMR after the ATPase reaction has proceeded for several minutes with zero-order kinetics. The reaction is started by addition of the aldehyde in a small volume of H2 18O, and the speed of washout of 18O by reversible dehydration relative to the rate of the ATPase reaction allows calculation of the rate constants if the hydration equilibrium constant is known from the proton NMR spectrum of the aldehyde. Dehydration rate constants (s-1 at pH 8-8.5, 0.1 M buffer, 25 degrees C) for the following aldehydes (all over 95% hydrated) and kinases used are as follows: D-glyceraldehyde with glycerokinase, 0.03; 2,5-anhydro-D-mannose 6-phosphate with fructose-6-phosphate kinase, 0.025; 2,5-anhydro-D-mannose or 2,5-anhydro-D-talose with fructokinase, 0.029 and 0.017, respectively; D-gluco-hexodialdose with hexokinase, 0.068. With betaine aldehyde and choline kinase or glyoxylate and pyruvate kinase, no 18O was transferred to phosphate during the ATPase reactions. However, the dehydration rate constant for glyoxylate (0.007 s-1 at pH 7 extrapolated to zero buffer concentration and up to 0.11 s-1 at pH 9.0 with 0.3 M buffer) was determined by extrapolating the initial rate of reduction of the free aldehyde catalyzed by lactate dehydrogenase to infinite enzyme levels.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Table 2 gives the most probable data for K hy = [hydrate]/[aldehyde] available in the literature. [31][32][33][34][35][36][37][38][39][40][41][42][43] Hydration in acidic solution is rapid compared with oxidation (k H = 500-800 dm 3 mol Ϫ 1 s Ϫ 1 for acetaldehyde 31,32,36,38,41 and 450-490 dm 3 mol Ϫ 1 s Ϫ 1 for propionaldehyde 32,36,41 ), i.e. the kinetic equation does not show whether the aldehyde or the hydrate is the reactive form.…”

Section: Kinetics In Acidic Solutionmentioning

confidence: 99%

“…For K hy we applied literature data [31][32][33][34][35][36][37][38][39][40][41][42][43] (given in Table 2); k 0 is the rate constant measured in neutral media, and therefore the two-parameter fitting of…”

Section: Kinetics In Alkaline Solutionmentioning

confidence: 99%

Oxidation of Aldehydes With Permanganate in Acidic and Alkaline Media

JÁKY¹,

SZAMMER²

1997

J. Phys. Org. Chem.

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The oxidation mechanism of aldehydes with permanganate was studied in acidic and alkaline media on acetaldehyde, propionaldehyde, pivalaldehyde (2,2Ј-dimethylpropanal) and chloral substrates. On addition of water to acetaldehyde dissolved in organic solvents the rate increased, and therefore it may be stated that the hydrate form is more reactive than the aldehyde form. Acid-catalysed nucleophilic addition of permanganate is suggested. In alkaline medium a mechanism based on electron abstraction from the alkoxy anion of the hydrate is proposed. Deprotonation constants of hydrate could be calculated..

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996. Kinetics of hydration of aliphatic aldehydes

Cited by 22 publications

References 0 publications

Aldehyde Recognition and Discrimination by Mammalian Odorant Receptors via Functional Group-Specific Hydration Chemistry

Aldehyde Recognition and Discrimination by Mammalian Odorant Receptors via Functional Group-Specific Hydration Chemistry

A novel method for determining rate constants for dehydration of aldehyde hydrates

Oxidation of Aldehydes With Permanganate in Acidic and Alkaline Media

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