Lawrence Hogge

A simple enzymatic method for the preparation of radiolabeled erucoyl-CoA and other long-chain fatty acyl-CoAs and their characterization by mass spectrometry

A simple two-step method for the biosynthesis of radiolabeled erucoyl-coenzyme A of high specific activity and other long-chain fatty acyl-coenzyme A (acyl-CoA) thioesters is reported. 1-14C-labeled erucic and oleic acids, as well as unlabeled ricinoleic and nervonic acids, were incubated at 35 degrees C with coenzyme A in the presence of ATP, MgCl2, and acyl-CoA synthetase (EC 6.2.1.3) from Pseudomonas spp. to yield the corresponding CoA thioesters. Following incubation, each thioester was purified by rapid passage through a disposable reverse-phase C18 extraction column. The overall yields were greater than 90% and the purities greater than 95%, based on the distribution of radioactivity, and chromatographic and spectral properties. Fast ion bombardment-mass spectrometry was employed to confirm the structures of the various acyl-CoAs.

The South-western USA and Northern Mexico one-seeded Junipers: their volatile oils and evolution

Abstract The composition of the volatile oils of Juniperus erythrocarpa, J. monosperma, J. monosperma var. gracilis and J. pinchotii are reported from analysis by capillary GC MS-computer search. Juniperus erythrocarpa appears to have two chemical types or races, one from southern Arizona-south-west New Mexico and the other from Mexico and trans-Pecos Texas. Juniperus monosperma var. gracilis contained aromatics from the phenyl propanoid pathway marking the first report of similar to J. monosperma var. gracilis , suggesting a nomenclatural change is needed for the latter taxon. The evolution within this complex has apparently been discordant between the morphology and the terpenoids.

Formation of trierucoylglycerol (trierucin) from 1,2-Dierucoylglycerol by a homogenate of microspore-derived embryos ofBrassica napus L

Homogenates of microspore-derived embryos of rape (Brassica napus L.) incubated with [1-14C]erucoyl-CoA and 1,2-dierucoylglycerol are able to assemble trierucoyl-glycerol (trierucin). In addition, radioactive triacylglycerols are formed by transferring [1-14C]-erucoyl moieties to endogenous lipid precursors. Stereospecific analysis of radioactive triacylglycerols revealed that labeled erucoyl moieties had been incorporated exclusively into thesn-1,3 positions with more than 95% of radioactivity in thesn-3 position. No incorporation of labeled erucic acid into thesn-2 position has been observed. All data agree with the involvement of 1,2-diacylglycerol acyltransferase (E.C. 2.3.1.20), which utilized 1,2-dierucoylglycerol as well as endogenous 1,2-diacylglycerols as acceptors of erucoyl moieties. This result is of particular interest for the genetic modification of rape and other Cruciferae for producing trierucin in their seed oils.

Stereospecific analysis and mass spectrometry of triacylglycerols fromarabidopsis thaliana (L.) heynh. columbia seed

Arabidopsis thaliana continues to be an excellent model organism for studying plant molecular genetics and biochemistry. In particular, the generation and analysis of mutant lines has facilitated the study of fatty acid biosynthesis, lipid bioassembly and the regulation of these processes. In view of its importance in understanding the pathways specific to seed storage lipid biosynthesis, we report here, for the first time, stereospecific and mass spectral analyses of the triacylglycerols present inA. thaliana (L.) Heynh. Columbia wild-type seed. The use of NH4+-chemical-ionization mass spectrometry/mass spectrometry is described as a powerful technique in analyzing even trace amounts of individual triacylglycerol species.

Isolation and characterization of β-d-glucan, heteropolysaccharide, and trehalose components of the basidiomycetous lichen Cora pavonia

Abstract Cora pavonia, a lichen having a basidiomycetous mycobiont, is rich in protein (36%), of which 10% is tyrosine. α,α-Trehalose is present and was isolated in 4.4% yield. The lichen was found to contain polysaccharides typical of basidiomycetes and different from those of ascomycetes and ascomycetous lichens. Isolated and characterized were a β- d -glucan and a heteropolysaccharide containing l -rhamnose, l -fucose, d -xylose, d -mannose, d -glucose, and d -galactose. The β- d -glucan was highly branched with 21% of nonreducing end-groups, contained 3-O-, 6-O-, and 3,6-di-O-substituted β- d -glucopyranosyl units, and had a main chain consisting of (1→3)- and (1→6)-links. The heteropolysaccharide component contained mainly mannose and xylose, having a mannose-containing nucleus and a main chain with preponderant (1→3)-linked α- d -mannopyranosyl residues. These were unsubstituted (10%), and 4-O- (10%) and 2,4-di-O-substituted (10%) with residues of β- d -xylopyranose. On methylation analysis of the heteropolysaccharide, a capillary column of DB-210 proved to be particularly useful for gas-liquid chromatographic resolution of partially O-methylated alditol acetates.

Gas chromatographic—mass spectrometric analysis of β-diketone-containing plant waxes : Use of trimethylsilyl ethers☆

Abstract A number of β-diketones and β-diketone-containing waxes have been trimethylsilylated and analyzed by gas chromatography—mass spectrometry. The trimethylsilyl enol ethers of β-diketones and hydroxy and oxo β-diketones are completely separated by gas chromatography. Mass spectrometry of these derivatives gives simpler fragmentation patterns than those obtained with untreated β-diketones so that structure determination of β-diketones and oxygenated β-diketones, including structural isomers, is considerably facilitated. Trimethylsilyl derivatives of free acids and alcohols formed at the same time are separated from each other and from hydrocarbons by gas chromatography and are also identified by mass spectrometry.

Chemosystematic studies of the western north american junipers based on their volatile oils

Abstract Six taxa of western North American denticulate leaved junipers were collected and their volatile leaf oils analysed. Two chemical forms of J. californica (‘A’ and ‘B’) previously reported were found to differ considerably in their concentration of α-pinene, sabinene, β-pinene, camphor and 4-terpineol. However, principal co-ordinate analysis revealed that the chemical forms of J. californica were the most similar taxa in the group and considerably more similar than the two varieties of J. occidentalis are to each other. This group of junipers appears to consist of two major subgroups: (1) J. occidentalis ; and (2) J. california, J. monosperma, J. osteosperma ; with J. osteosperma being closely related to the northern form of J. californica (:A.) and J. monosperma being most closely related to the southern form of J. californica (‘B’).

Gas chromatographic-mass spectrometric characterization of some fatty acids from white and interior spruce

Abstract The objective of this work was to determine the fatty acid composition of white and interior spruce seeds. Fatty acid methyl ester derivatives obtained from the seed oils were analyzed by gas chromatography. Elution times for some of the spruce fatty acid methyl ester derivatives did not correspond to those of available standards. Diethylamide derivatives were prepared and analyzed by gas chromatography-mass spectrometry. The electron-impact mass spectral fragmentation patterns of the fatty acids of interest indicated cis-11-18:1, cis-5, cis-9-18:2 and cis-5, cis-9, cis-12-18:3.

Metabolism of (+) abscisic acid to dihydrophaseic acid-4′-β-d-glucopyranoside by sunflower embryos

Abstract (+)-[2- 14 C]Abscisic acid [(+) ABA], prepared from ±-[2- 14 C] ABA by HPLC on a chiral column, at an initial concentration of 10 μM, was absor

Characterization of abscisic acid and metabolites by combined liquid chromatography-mass spectrometry with ion-spray and plasma-spray ionization techniques

Abstract Liquid chromatographic-mass spectrometric methods have been developed for the characterization of abscisic acid (ABA) and metabolites in plant cell cultures using plasma-spray and ion-spray ionization techniques. Both techniques provide useful mass spectral data for ABA and its acidic metabolites. The most intense ions in these spectra are represented by [M + H] + and [M + H − H 2 O] + . The limit of detection for ABA, using plasma-spray and ion-spray was 5 and 9 ng, respectively, for full scans and 0.5 and 1 ng, respectively, for selected-ion recording of m/z 265, the protonated molecular ion. Ion-spray also provided intense protonated molecular ions for the neutral ABA metabolites whereas plasma-spray did not. Spectra acquired using both techniques showed intense ions indicating the presence of the ABA moiety in these neutral conjugates.