Neutral lipids ofXanthium strumarium seeds

Chemical, chromatographic, and spectral methods are used for the first time to analyze neutral lipids, ordinary and hydroxylated fatty acids, and lipophilic components ofXanthium strumarium L. seeds.S. Yu. Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (99871) 120 64 75. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 103–105, March–April, 2000.     

Characterization of organosulfates from the photooxidation of isoprene and unsaturated fatty acids in ambient aerosol using liquid chromatography/(-) electrospray ionization mass spectrometry

In the present study, we have characterized in detail the MS(2) and MS(3) fragmentation behaviors, using electrospray ionization (ESI) in the negative ion mode, of previously identified sulfated isoprene secondary organic aerosol compounds, including 2-methyltetrols, 2-methylglyceric acid, 2-methyltetrol mononitrate derivatives, glyoxal and methylglyoxal. A major fragmentation pathway for the deprotonated molecules of the sulfate esters of 2-methyltetrols and 2-methylglyceric acid and of the sulfate derivatives of glyoxal and methylglyoxal is the formation of the bisulfate [HSO(4)](-) anion, while the deprotonated sulfate esters of 2-methyltetrol mononitrate derivatives preferentially fragment through loss of nitric acid. Rational interpretation of MS(2), MS(3) and accurate mass data led to the structural characterization of unknown polar compounds in K-puszta fine aerosol as organosulfate derivatives of photooxidation products of unsaturated fatty acids, i.e. 2-hydroxy-1,4-butanedialdehyde, 4,5- and 2,3-dihydroxypentanoic acids, and 2-hydroxyglutaric acid, and of alpha-pinene, i.e. 3-hydroxyglutaric acid. The deprotonated molecules of the sulfated hydroxyacids, 2-methylglyceric acid, 4,5- and 2,3-dihydroxypentanoic acid, and 2- and 3-hydroxyglutaric acids, showed in addition to the [HSO(4)](-) ion (m/z 97) neutral losses of water, CO(2) and/or SO(3), features that are characteristic of humic-like substances. The polar organosulfates characterized in the present work are of climatic relevance because they may contribute to the hydrophilic properties of fine ambient aerosol. In addition, these compounds probably serve as ambient tracer compounds for the occurrence of secondary organic aerosol formation under acidic conditions.     

OXYGENATED FATTY ACIDS FROM NEUTRAL LIPIDS OF Artemisia leucodes SEEDS

Three epoxy-, fifteen monohydroxy-, and three dihydroxyacids from lipids ofArtemisia leucodesSch. Seeds were identified using chemical, chromatographic, and spectral analyses.     

Neutral lipids from seeds of Asteraceae plants

Lipids from seeds of three plants of the Asteraceae family, Cousinia franchetii, Arctium leiospermum, and Rhaponticum integrifolium, were studied. The principal constituents of lipids from the three plants were shown to be acylglycerides of ordinary fatty acids and oxygenated fatty acids using chemical and chromatographic analyses. The composition of the ordinary unoxidized and epoxy acids was determined by GC. Presented at the 7th International Symposium on the Chemistry of Natural Compounds, October 16–18, 2007, Tashkent, Uzbekistan __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 115–117, March–April, 2008.     

Influence of Reduced Temperature on Lipid Composition of <Emphasis Type="Italic">Viburnum opulus</Emphasis> Seeds

The influence of reduced temperature (frost) on the lipid composition of Viburnum opulus seeds was studied. Low temperatures changed lipid metabolism by forming hydroxyglycerides in NL, lowering significantly the GL and PL contents, and changing their class composition. The structures of hydroxyacids in the hydroxyglycerides were established. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 523–528, November–December, 2005.     

Unsubstituted and Hydroxy Substituted Fatty Acids in a Recent Lacustrine Sediment: (Lake Léman,Geneva, Switzerland)

Abstract

Unsubstituted as well as α-, β- and (ω-1)-hydroxy substituted fatty acids were analyzed in a 5 m long sediment core taken from Lake Léman (Switzerland). All these acids occur in three forms: unbound, bound and tightly bound and our results show that there is no conversion from one form to another. The fact that below a burial depth of 30 cm the abundance profiles show no decreasing trend indicates that the diagenetic reactions do not operate below that depth. On the basis of our results, compared with other published data, source correlations are postulated for each of the acid classes. The presence of unsubstituted monounsaturated acids in the C₂₀ to C₃₂ range probably indicates that long chain fatty acids cannot be considered only as indicators of inputs from higher plants. Finally, C₂₇, C₂₉ and C₃₁ (ω-1)-hydroxyacids with unusual structures have also been found in these sediments, as well as 2-methyl nonacosanoic acid; their origin has not yet been established.     

Attempting to remove the substrate inhibition ofL-lactate dehydrogenase fromBacillus stearothermophilus by site-directed mutagenesis

L-lactate dehydrogenase (LDH) catalyzes the interconversion of an oxoacid (pyruvate) and hydroxy-acid (lactate) using the NADH/NAD⁺ pair as a redox cofactor. The enzyme has a commercial significance, as it can be used to produce chiral building blocks for the synthesis of key pharmaceuticals and agrochemicals. However, the substrate inhibition which is due to an abortive NAD⁺-pyruvate complex reducing the steady state concentration of functional LDH limits its use in industry. This substrate inhibition can be overcome by weaking the binding of NAD⁺. The conserved aspartic acid residue at position 38 was replaced by the longer basic arginine side chain (D38R) using PCR based overlap extension mutagenesis technique in the hope of weakening NAD⁺-binding. The mutant gene was overexpressed in theEscherichia coli high-expression vector pKK223-3 in JM105 cells; then, the mutant protein was produced. Comparing the effect of substrate inhibition in the arginine-38 mutant with wild-type, substrate inhibition is decreased threefold.