(n.) One of a large class of organic substances resembling the aldehydes, obtained by the distillation of certain salts of organic acids and consisting of carbonyl (CO) united with two hydrocarbon radicals. In general the ketones are colorless volatile liquids having a pungent ethereal odor.
Example Sentences:
(1) The enzyme was solubilized by Triton X-100 and purified approximately 480-fold by gel filtration and affinity chromatography on alanine methyl ketone-AH-Sepharose 4B.
(2) Urinalysis revealed a low pH, increased ketones and bilirubin excretion, dark yellowish change in color, the appearance of "leaflet-shaped" crystals and increased red blood cells and epithelial cells in the urinary sediment, increased water intake, decreased specific gravity and decreased sodium, potassium and chloride in the urine.
(3) The infusion of sodium acetoacetate resulted in a 10- to 15-fold increase in circulating concentrations of ketone bodies, which were similar in magnitude in normal subjects and diabetic patients.
(4) Results of repeated visual readings spread over three different color blocks for certain concentrations of glucose, ketone, and protein, whereas repeated instrumental readings were never spread greater than two color blocks.
(5) The plasma concentrations of alanine and proline as well as other amino acids increased as the blood ketone body ratio decreased.
(6) Trifluoromethyl ketone dipeptide analogues are good inhibitors of angiotensin converting enzyme.
(7) As a conclusion sec-butanol, probably through its metabolite methyl-ethyl-ketone, is the most potent inducer of microsomal cytochrome P-450 in liver and kidney while iso-butanol does not alter total cytochrome P-450.
(8) A model of increased microvascular permeability pulmonary edema was developed in chronically instrumented unanesthetized sheep using perilla ketone (PK).
(9) Administration of different brain fuels--glucose, mannose, fructose, or the ketone beta-hydroxybutyrate--reduced hippocampal damage induced by coadministration of GCs and either of 2 different neurotoxins (kainic acid and 3-acetylpyridine).
(10) We report the effects of n-alkanols (n-butanol to n-octanol), methyl carboxylic esters (methyl propionate to methyl octanoate) and n-alkyl ketones (2-pentanone to 2-nonanone) on a fast reflex escape response to a mechanical stimulus in Gammarus.
(11) Examination of other potential inhibitors revealed a rank order of potency against calpain to be: peptidyl sulphonium methyl ketones > fluoromethyl ketones, diazomethyl ketones >> acyloxymethyl ketones, an order which differs sharply from that found for cathespin B.
(12) Epigalanthamine, a diastereomer of GAL, was 130-times less potent in vitro in its effect on acetylcholinesterase (AChE) in erythrocytes than the parent compound, and it did not differ significantly from the ketone galanthaminone.
(13) Also, a significant correlation was found between the levels of urine glucose and ketones and the level of acyl carnitine.
(14) This is in contrast to fasting adult dogs, which maintain glucohomeostasis and show only slightly decreased insulin levels, normal glucagon levels and a moderate increase of plasma ketone bodies.
(15) The following processes are discussed in this article: enzyme-catalysed hydrolyses of carboxylic acid esters and amides, phosphate esters, nitriles and epoxides; esterification and inter-esterification reactions catalysed by enzymes; reduction of ketones to secondary alcohols using whole-cell systems or isolated dehydrogenases; oxidation of alicyclic and aromatic substrates using mono-oxygenases and dioxygenases in bacteria and fungi including enzyme-catalysed Baeyer-Villiger oxidations; aldol reactions, formation of optically active cyanohydrins and enzyme-catalysed acyloin type reactions.
(16) The paint base consisted primarily of toluene and methyl ethyl ketone.
(17) Ketonic bodies participate in the power supply of cortex functions of satisfied one-day pigs but their contribution to the nerve tissue power of fasting one-and five-day pigs is insignificant.
(18) Mechanism-based inhibition of myocardial cytosolic calcium-independent phospholipase A2 by Compound 1 was established by demonstrating: 1) time-dependent irreversible inactivation; 2) covalent binding of [3H]Compound 1 to the purified phospholipase A2; 3) ablation of covalent binding of [3H]Compound 1 after chemical inactivation of phospholipase A2 enzymic activity; 4) identical inhibition of myocardial phospholipase A2 by Compound 1 in the absence or presence of nucleophilic scavengers; 5) Compound 1 is a substrate for myocardial calcium-independent phospholipase A2 resulting in the generation of the electrophilic alpha-bromomethyl ketone; 6) phospholipase A2 inhibition requires the in situ generation of the reactive electrophile (i.e.
(19) Inhibition by phenylmethanesulfonyl fluoride and N alpha-p-tosyl-L-lysine chloromethyl ketone indicates the presence of serine and histidine residues in the active center, respectively.
(20) In addition, adrenal S-adenosylmethionine (SAM) and blood ketone bodies were determined Sections of adrenals were evaluated by electron microscopy for histopathological changes.
Tautomerism
Definition:
(n.) The condition, quality, or relation of metameric substances, or their respective derivatives, which are more or less interchangeable, according as one form or the other is the more stable. It is a special case of metamerism; thus, the lactam and the lactim compounds exhibit tautomerism.
Example Sentences:
(1) The coupled dienone-phenol re-arrangement and keto-enol tautomerism of this quinone methide produce the observed 3,4-dihydroxybenzaldehyde.
(2) On the other hand, results indicate that the protonation of formycin and its derivatives at the N1 atom leads to a change in their tautomeric preference from N7-H to N8-H.
(3) The inhibitor trapping system, however, prevents the inactivation of succinate dehydrogenase under the conditions when the rate of tautomeric oxaloacetate enol in equilibrium oxaloacetate ketone interconversion is high.
(4) In contrast, equilibria of ring chain tautomerism and covalent hydration of aldoses are almost completely insensitive to the polarity of their surroundings.
(5) The importance of both tautomerism and protonation reactions in the mechanism of action of adenosine deaminase is studied by means of a quantitative structure activity relationships strategy.
(6) The possibility that this product is an equilibrium mixture with the tautomeric 4-hydroxycyclophosphamide has not been as yet defintely ruled out.
(7) In addition to being a possible mechanism for alteration of hydrogen bonding in oxidized DNA, this type of interaction gives a better understanding into N7-N9 tautomerism of adenine.
(8) The product 3-fluorooxalacetate is thus released from phosphoenolpyruvate carboxykinase as the keto form and is reduced more rapidly by reduced nicotinamide adenine dinucleotide with malate dehydrogenase than by the occurrence of tautomerization.
(9) These results strongly suggest that the anomeric, epimeric, and tautomeric form of the sugar phosphate substrates favored by both enzymes is the beta-D-fructofuranose form.
(10) Tautomerization of DOPA quinone to dehydroDOPA may thus be a factor in the sclerotization of natural structures incorporating DOPA containing proteins.
(11) For the complex formed between [5,5-2H,5-13C]ALA and methyl methanethiosulfonate (MMTS) modified PBG synthase, which does not catalyze PBG formation but can form a Schiff base adduct, the chemical shift of 44.2 ppm (line width 92 Hz) identifies an imine structure as the predominant tautomeric form of the Schiff base.
(12) delta 5-3-Ketosteroid isomerase (EC 5.3.3.1) catalyzes the isomerization of delta 5-3-ketosteroids to delta 4-3-ketosteroids by a conservative tautomeric transfer of the 4 beta-proton to the 6 beta-position with Tyr-14 as a general acid and Asp-38 as a general base [Kuliopulos, A., Mildvan, A. S., Shortle, D., & Talalay, P. (1989) Biochemistry 28, 149-159].
(13) The results are consistent with evidence for the formation of the first tetrahydropterin intermediate by a tautomerization without any requirement for NADPH.
(14) Its function is probably to maintain the orientation and tautomeric state of the imidazole ring of histidine-159.
(15) This suggests that a stable AP:C base mispair via two hydrogen bonds can be formed with the imino tautomer of C. These results stress the importance of the imino form of C in AP-induced mutagenesis and support the 'trigger mechanism', in which formation of one hydrogen bond between AP and C is considered to stimulate the tautomeric shift of AP or C. The calculated relative stabilities of various base pairs and mispairs were in good agreement with experimental findings.
(16) Whereas O6-MeGua did not form hydrogen bonds with cytosine (via usual, wobble, or unusual tautomeric structures), it did form a 1:1 hydrogen-bonded complex with protonated cytosine.
(17) Amide-imide tautomerism enables a cleanup of the extract.
(18) Ultraviolet and infrared spectrophotometric techniques have been utilized to demonstrate that the monoanionic form of 2-thiouracil in aqueous medium consists of an equilibrium mixture of two tautomeric monoanions, one due to dissociation of the N1 proton, the other to dissociation of the N3 proton, in the approximate ratio 1:1.
(19) Combined use of mass spectroscopy and 1H- and 13C-NMR spectroscopy established that it is the 4,8-anhydro derivative of N-acetylneuraminic acid and that in solutions it exists in two tautomeric forms.
(20) As a result of a concerted proton (tautomeric) shift in the linked residues of the hydrogen-bond chain, which includes the bound molecule, a charge separation occurs.