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At least 235 records · Page 13Linked to original sources
PubMed2001

Site-specific cleavage of a protein via introducing a hydroxy acid derivative in the main chain by using four-base codon/anticodon pairs.

Site-specific incorporation of the tyrosine isostere (2-Hydroxy-3-(4-hydroxy-phenyl)-propionic acid) into streptavidin was accomplished by in vitro frameshift suppression of a CGGG 4-base mutation with a chemically acylated frameshift suppressor tRNA(cccg). The mutant, in which the backbone amide linkage is replaced by an ester linkage, is hydrolyzed under neutral condition. The cleavage rate of the protein backbone at a single-predetermined site was strongly depended on the incorporated position of the isostere.

Anticodon↗
PubMed1982

Characteristic lipids of Bordetella pertussis: simple fatty acid composition, hydroxy fatty acids, and an ornithine-containing lipid.

The lipids and fatty acids of Bordetella pertussis (phases I to IV) were analyzed by thin-layer chromatography, gas-liquid chromatography, and mass spectrometry and compared with those of B. parapertussis and B. bronchiseptica. The major lipid components of the three species were phosphatidylethanolamine, cardiolipin, phosphatidylglycerol, lysophosphatidylethanolamine, and an ornithine-containing lipid. The ornithine-containing lipid was characteristic of the genus Bordetella. The fatty acid composition of the total extractable cellular lipids of B. pertussis was mostly hexadecanoic and hexadecenoic acids (90%) in a ratio of about 1:1. The hexadecenoic acid of B. pertussis was in the cis-9 form. The fatty acid composition of the residual bound lipids was distinctly different from that of the extractable lipids, and residual bound lipids being mainly 3-hydroxytetradecanoic, tetradecanoic, and 3-hydroxydecanoic acids, with 3-hydroxydodecanoic acid occurring in some strains. It was determined that the 3-hydroxy fatty acids were derived from lipid A. The fatty acid composition of the total extractable cellular lipids of B. parapertussis and B. bronchiseptica, mainly composed of hexadecanoic and heptadecacyclopropanoic acid, differed from that of B. pertussis. Although the fatty acid composition of the residual bound lipids of B. parapertussis was similar to that of the residual bound lipids of B. pertussis, 2-hydroxydodecanoic acid was detected only in the bound lipids of B. bronchiseptica.

Bordetella↗
PubMed1976

[Alpha-hydroxy-acid dehydrogenase activity in Trypanosoma cruzi].

Crude extracts of culture forms of epimastigotes, Tulahuén strain, showed activity to catalyze the reaction alpha-ketocid in equilibrium alpha-hydroxyacid linked to nicotinamide adenine dinucleotide (NAD). The enzyme utilizes the following substrates: alpha-ketobutyrate, alpha-ketoisovalerate, alpha-keto-beta-methylvalerate, alpha-ketocaproate, alpha-ketoisocaproate, alpha-ketoglutarate and pyruvate. Kinetics for the three last substrates were of the Michaelian type. For the other ketocids, curves of activity against substrate concentration exhibited a bimodal character. Km and V values for alpha-ketoisocaproate were strikingly higher than those for the other substrates. Electrophoretic separation of extracts on polyacrylamide gel and specific staining showed a single zone of enzymatic activity with similar mobility for all the alpha-OH-acids tested. This finding would indicate that the same protein is responsible for the reaction. The observations presented demonstrate that culture forms of Trypanosoma cruzi possess the ability to interconvert pyruvate in equilibrium lactate and to regenerate NAD in anaerobiosis. Although the physiological significance of the reaction with alpha-ketoacids other than pyruvate is not known, similarity of substrate of substrate spectrum between alpha-OH-acid dehydrogenase from Trypanosoma cruzi and lactate dehydrogenase ioenzyme X from mammalian and avian spermatozoa is interesting. Perhaps activity of flagella requires analogous metabolic pathways.

Alcohol Oxidoreductases↗
PubMed1992

Prebiotic sugar synthesis: hexose and hydroxy acid synthesis from glyceraldehyde catalyzed by iron(III) hydroxide oxide.

Iron(III) hydroxide oxide [Fe(OH)O] efficiently catalyzed the condensation of 25 mM DL-glyceraldehyde to ketohexoses at 25 degrees C (pH 5-6). At 16 days the yields were sorbose (15.2%), fructose (12.9%), psicose (6.1%), tagatose (5.6%), and dendroketose (2.5%) with 19.6% of triose unreacted. Analysis at 96 days showed no decomposition of hexoses. Under these conditions Fe(OH)O also catalyzed the isomerization and rearrangement of glyceraldehyde to dihydroxyacetone and lactic acid, respectively. In these reactions, about 10% of the glyceraldehyde was oxidized to glyceric acid with concurrent reduction of the iron(III) to iron(II). The partial reduction of Fe(OH)O did not noticeably reduce its ability to catalyze hexose synthesis. The relationship of these results to prebiotic sugar synthesis is discussed.

Carbohydrates↗
PubMedDate not supplied

Mild, solvent-free omega-hydroxy acid polycondensations catalyzed by candida antarctica lipase B.

Immobilized Candida antarctica Lipase B (Novozyme-435) was studied for bulk polyesterifications of linear aliphatic hydroxyacids of variable chain length. The products formed were not fractionated by precipitation. The relative reactivity of the hydroxyacids was l6-hydroxyhexadecanoic acid approximately 12-hydroxydodecanoic acid approximately 10-hydroxydecanoic acid (DPavg congruent with 120, Mw/Mn 6-hydroxyhexanoic acid (DPavg congruent with 80, Mw/Mn < or = 1.5, 48 h, 90 degrees C). Remarkable improvements in molecular-weight buildup resulted from leaving water in the reaction. By 4 h, without application of vacuum, the DPavg for 12- and 16-carbon hydroxyacids was about 90. In contrast, with identical substrates and water removal, the DPavg at 4 h was about 23. Large differences in the molecular-weight build up of 12-hydroxydodecanoic acid were observed for catalyst concentrations (%-by-wt relative to monomer) of 0.1, 0.5, 1, and 10. Nevertheless, by 24 h, with 1% catalyst containing 0.1% lipase, poly(12-hydroxydodecanoic acid) with Mn 17 600 was formed. For 12-hydroxydodecanoic acid polymerization at 90 degrees C, the catalyst activity decreased by 7, 18, and 25% at reaction times of 4, 24, and 48 h, respectively. Furthermore, the retention of catalyst activity was invariable as a function of the substrates used.

Candida↗
PubMedDate not supplied

A survey of consumer cosmetic products and salon preparations for alpha hydroxy acids.

The Food and Drug Administration has completed a survey of consumer and salon/professional cosmetic products for glycolic and lactic acids, and product pH, to determine conformity with recommended levels established by the Cosmetic Ingredient Review (CIR). In twenty-five consumer products, concentrations of glycolic and lactic acid ranged from 1.1% to 8.7%. Two products had pHs lower than the recommended minimum of 3.5. In seventeen salon/professional products, glycolic and lactic acids were found at levels ranging from 0.9% to 28.5%. Two salon products had pHs significantly lower than the 3.0 recommended by the CIR. About half of the products contained either a sunscreen or a recommendation for the use of a sunscreen.

Chromatography, High Pressure Liquid↗
PubMed1998

Capillary zone electrophoresis in normal or reverse polarity separation modes for the analysis of hydroxy acid oligomers in neutral phosphate buffer.

Capillary zone electrophoresis (CZE) with neutral phosphate buffer as the background electrolyte was used to analyse water-soluble oligomers obtained by polycondensation of racemic lactic acid. Two CZE separation modes were tested. The first mode was based on normal separation (injection at the anodic side) using a fused-silica capillary. Eight peaks were observed within a 60-min migration time range. They were ascribed to dimer and higher water-soluble oligomers. Peaks from dimer to tetramer were split due to sensitivity for the fine structures at the level of the distribution of chiral lactic acid moieties in oligomer chains. The second mode was based on reverse separation (injection at the cathodic side) using a fused-silica capillary modified by adsorption of a polycation on its inner wall. Under these conditions, oligomers were rapidly separated without peak splitting. Considering the forces which are involved in CZE, data were plotted as a function of 1/t scale, according to the equation [signal]=f((-1)(k)/t) where k=0 and k=1 for normal and reverse separation modes, respectively. Such a plot allowed direct comparison between the various runs after a simple translation along the 1/t axis, regardless of the separation mode and the variation of electroosmotic flow. The second separation mode allowed separation of 3-hydroxybutyric acid and 6-hydroxyhexanoic acid oligomers. For the former series of oligomers, a side reaction generating crotyl bonds was observed due to the high sensitivity of CZE. It was shown that separation was governed by the ratio charge/mass of the oligoesters whatever their structure.

Buffers↗
PubMed1996

Alpha hydroxy acids in skin care.

Although not surgery in the traditional sense, skin care offers the ability to treat patients with a wide range of skin pathology. Skin care is another facet in facial rejuvenation, whose magnitude will increase as the pathophysiology and treatment of photoaging and other skin conditions becomes better understood. Patient satisfaction has been overwhelming for physician-directed skin care, but as the number of products, regimens, and adjuncts increase exponentially, we must emphasize a well-founded, scientific approach to the individual patient's pathology.

Acne Vulgaris↗
PubMed1992

Simultaneous determination of simvastatin and its hydroxy acid form in human plasma by high-performance liquid chromatography with UV detection.

Simvastatin (SV), an analogue of lovastatin, is the lactone form of 1',2',6',7',8',8a'-hexahydro-3,5-dihydroxy-2',6'-dimethyl-8'(2'',2''-di met hyl-1''-oxobutoxy)-1'-naphthalene-heptanoic acid (SVA) which lowers plasma cholesterol by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase. A fast, simple and accurate method for determining SV and SVA concentrations in human plasma has been developed and validated for use in the analysis of plasma samples from patients and healthy volunteers. This method involves an extraction procedure using a mixture of acetonitrile-water and reversed-phase high-performance liquid chromatography with UV detection. The procedure was linear from 20 to 1000 ng ml-1 for SV and from 25 to 1000 ng ml-1 for SVA, respectively. The method was accurate with relative errors of 5.0, 2.1 and 3.2% for human plasma controls containing 50, 250 and 500 ng ml-1 of SV, respectively. The corresponding precision was 2.3, 1.8 and 1.0% (RSD%). Similarly, relative standard deviations less than 2.3% and relative errors of less than 5.2% were obtained from human plasma controls containing SVA at identical concentrations. The method is suitable for pharmacology and pharmacokinetic studies of simvastatin.

Blood Proteins↗
PubMed1985

Circulating hydroxy fatty acids in familial Mediterranean fever.

Episodes of fever, serositis, and arthritis in familial Mediterranean fever (FMF) suggested circulating mediators of acute inflammation (e.g., neutrophil activation). The mean serum neutrophil-aggregating activity of 51 FMF patients was 2.5 +/- 0.2 cm2/min, compared to 1.0 +/- 0.1 cm2/min in 20 normal controls (P less than 0.0002). Lipid extracts of FMF sera retained neutrophil-aggregating activity and had UV absorbance peaks at 269 and 279 nm, indicating the presence of lipids with a conjugated triene structure. Chromatography of extracts yielded peaks that were coeluted with reference dihydroxyicosatetraenoic acids, had UV absorbance peaks at 259, 269, and 279 nm, and possessed neutrophil-aggregating activity. The presence of leukotriene B4 was excluded by chromatography following methyl-esterification. Monohydroxy compounds identified in FMF extracts by gas chromatography/mass spectrometry included 5-hydroxyicosatetraenoic acid, and 9- and 13-hydroxyoctadecadienoic acids. Hydroxy acids were present in 19 of 31 FMF sera and absent in extracts of sera from 8 patients with active systemic lupus erythematosus, 7 with fever from infection, and 12 normal controls. The finding of circulating mono- and dihydroxy fatty acids in FMF suggests that defects in the formation or elimination of these compounds might play a role in the pathogenesis of FMF.

Cell Aggregation↗
PubMed2000

Dynamic kinetic resolution of alpha-hydroxy acid esters

[formula: see text] Enzymatic resolution in combination with ruthenium-catalyzed racemization of the substrate led to dynamic kinetic resolution of alpha-hydroxy esters in good yields and excellent ee's. Studies of different parameters showed that the best results were obtained using Pseudomonas cepacia lipase, ruthenium catalyst 3, and 4-chlorophenyl acetate as acyl donor in cyclohexane.

Journal Article↗