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Biomedical subjects

F Snyder

Publications and source records attributed to F Snyder.

At least 163 records · Page 9Linked to original sources
PubMed1976

Stimulation of the microsomal alkylglycerol monooxygenase by catalase.

Liver cytosol contains a heat-sensitive nondialyzable soluble factor necessary for maximal activity of the alkylglycerol monooxygenase present in rat liver microsomes. In this report, we demonstrate that the stimulatory component in rat liver supernatant is catalase. Catalase functions to protect the enzyme from inactivation by H2O2 in addition to its documented ability to retard the noenzymatic oxidation of the pterin cofactor. The protective effect of catalase on alkylglycerol monooxygenase and on the aromatic amino acid hydroxylase systems indicates that H2O2 sensitivity is a general feature of pterin-dependent hydroxylases.

Animals↗
PubMed1976

Recorded and reported sleep in chronic primary insomnia.

Sleep polygraph and questionnaire data of 18 chronic primary insomniacs were compared with those of 18 age- and sex-matched controls. The insomniacs had significantly longer sleep latencies, less total sleep, less sleep efficiency, more terminal wake time, and less delta sleep. There were significant discrepancies between the insomniacs' and controls' subjective assessments of their sleep and the sleep-polygraph data, but in opposite directions. The insomniacs' recorded sleep also showed more night-to-night variability than that of the controls. However, the controls, in contrast to the insomniacs, reported sleeping worse in the laboratory than at home. Significant differences between insomnia subtypes validly reflected the insomniacs' subjective complaints and were generally in accord with expectations based on them.

Adult↗
PubMed1976

Transfer of methyl groups from N-dimethylnitrosamine to glycerolipids in rat liver.

We have examined the in vivo labeling of lipids after a single intraperitoneal injection of the carcinogen, (C14) dimethylnitrosamine, into rats. Liver was most active in incorporating (C14) methyl groups into lipids (0.91% of the injected dose) and 80% of the activity appeared in sn-3-phosphatidyl-choline. Chromatographic analysis of the products (and derivatives) formed after treatment of the (C14) phosphatidylcholine with phospholipase A2 (EC 3.1.1.4) and phospholipase C (EC 3.1.4.3) demonstrated that 89% of the radioactivity was in the choline moiety. These results indicate the transfer of methyl groups to lipids occurred via the lipid methylation pathway that converts phosphatidylethanolamine to phosphatidylcholine.

Animals↗
PubMed1976

Mass spectral identification of 2-(O-acyl)hydroxy fatty acid esters in the white portion of the rabbit Harderian gland.

A major lipid component of white portion of the rabbit harderian gland has been shown to be a mixture of 2-(O-acyl)hydroxy fatty acid esters. The fatty acid moieties in this lipid class are exclusively saturated and range in chain length from C14:0 to C22:0, with C16:0 being the major component (65%). The fatty alcohols are also saturated and composed primarily of C20:0, C21:0, and C22:0 chains. The hydroxy fatty acids are composed of C14:0, C15:0, and C16:0 and mass spectroscopy combined with chemical techniques placed the hydroxyl group at the 2-carbon. 2-(O-acyl)Hydroxy fatty acid esters are not found in the pink portion of the rabbit harderian gland nor have they been reported to occur in harderian glands or other species.

Animals↗
PubMed1976

Aliphatic Chains of Esterified Lipids in Isolated Eyespots of Euglena gracilis var. bacillaris.

Isolated eyespot granules of Euglena gracilis Klebs var. bacillaris Pringsheim contained approximately 6% lipids (based on protein). Separation of the lipid extracts by thin layer chromatography revealed four major fractions: wax esters, triacylglycerols, free fatty acids, and phospholipids. Methanolysis of each fraction yielded between 27 and 29 different fatty acids ranging from 12:0 to 22:6. Acetates of the fatty alcohols of the wax fraction consisted of 11:0 to 18:0 carbon chains, with 14:0 being the major component; unsaturated alcohols were not detected.

Journal Article↗
PubMed1976

Rapid screening of lipid metabolism in monolayer cell cultures.

Monolayer cell cultures grown on coverslips in the presence of radioactive lipid precursors were embedded in silica gel layers for extraction and resolution of the labelled products directly by thin-layer chromatography. The method permits rapid screening of lipid metabolism in tissue cultures with a small number of cells.

Carbon Radioisotopes↗
PubMed1975

Incorporation and subcellular distribution of an unnatural phospholipid base-analog, N-isopropyl-ethanolamine, in rat liver.

An unnatural phospholipid, phosphatidyl-N-isopropylethanolamine, was isolated from rat liver after intraperitoneal injections of N-isopropylethanol-amine; it was identified on the basis of enzymic, chemical, and chromatographic analyses. Although this phospholipid was formed at the expense of phosphatidylcholine and phosphatidylethanolamine, its fatty acid composition did not resemble either of these lipids. Microsomes, mitochondria, and plasma membranes contained significant amounts (up to 9%) of this unusual phospholipid. Radioisotope incorporation experiments suggest that the N-isopropylethanol-amine containing phospholipid is rapidly equilibrated between microsomes and mitochondria and more slowly with surface membranes.

Animals↗
PubMed1975

Rapid purification of phospholipase A2 from Crotalus adamanteus venom by affinity chromatography.

We have used alkyl ether analogs of ethanolamine and choline phospholipids as ligands to purify phospholipase A2 (EC 3.1.1.4) from Crotalus adamanteus venom by affinity chromatography. One of the affinity columns was prepared with rac-1-(9-carboxy)nonyl-2-hexadecylglycero-3-phosphocholine linked to AH-Sepharose 4B via the carboxyl group. Specific adsorption of phospholipase A2 to this column was achieved in buffer containing Ca2+, and the enzyme was eluted in buffer containing EDTA. The two enzymes from this venom were prepared in good yield (greater than 90%), and were homogeneous as judged by polyacrylamide gel electrophoresis. Retention of phospholipase A2 did not occur when the initial irrigant was devoid of Ca2+. These results support the compulsory ordered mechanism for this enzyme proposed by Wells ((1972), Biochemistry 11, 1030-1041) on the basis of kinetic considerations. The second affinity support was prepared with 1,2-dihexadecyl-sn-glycero-3-phosphoethanolamine attached through the amine moiety to CH-Sepharose 4B. Specific adsorption of phospholipase A2 to this column did not occur. These data indicate that the phospholipid base group must be accessible to the enzyme for optimal binding, and that modifications in the alkyl side chains are more desirable when designing affinity matrices for purification of enzymes involved in phospholipid metabolism.

Animals↗
PubMed1975

A short-chain acyl-CoA: 1-alkyl-2-acyl-sn-glycerol acyltrasnferase from a microsomal fraction of the rabbit Harderian gland.

The 3-position of the alkyldiacylglycerols from the pink portion of the rabbit harderian gland is occupied exclusively by isovaleric acid. We describe a microsomal 1-alkyl-2-acyl-sn-glycerol acyltransferase from this gland which specifically incorporates short-chain acyl-CoA's into the 3-position of alkylacyl-glycerols. The enzyme is most active in the presence of CoA esters with chain lengths similar to isovaleric acid and is inactive in the presence of acetyl CoA and long-chain acyl-CoA's. No evidence was found for an enzyme that would transfer long-chain acyl-CoA's to the same substrate. The specificity of this acyltransferase can account for the exclusion of long-chain acyl moieties from the 3-position of the alkyldiacylglycerols in the harderian gland of rabbits.

Acyltransferases↗
PubMed1975

Metabolism of alkyldihydroxyacetone phosphate in rat brain.

Alkyldihydroxyacetone-P is the first detectable product in the biosynthetic pathway for ether-linked glycerolipids that eventually leads to the formation of ethanolamine plasmalogens, a major constituent of myelin. During early postnatal development, the specific activity of NADPH2:alkyldihydroxyacetone-P oxidoreductase in microsomes from rat brain is maximum at 4-5 days after birth, the time when the specific activity of the enzymes that synthesize alkyldihydroxyacetone-P also peaks. For the oxidoreductase assay, we developed a thin-layer chromatographic method that separates alkyldihydroxyacetone-P as the dinitrophenylhydrazine derivative from its reduced product (alkylglycerol-P), with excellent resolution. Phosphohydrolases associated with brain microsomes exhibit optimal pH maximums at 5.2-5.6 and 7.5-7.8 for all three substrates tested -- alkyldihydroxyacetone-P, alkylglycerol-P and alkylacylglycerol-P. Alkylglycerol-P was most readily dephosphorylated under all experimental conditions. The enzyme(s) that dephosphorylates alkyldihydroxyacetone-P and alkylglycerol-P have similar properties with respect to Mg-2+ or EDTA; with both substrates, Mg-2+ had no effect and EDTA was highly stimulatory. In contrast, EDTA strongly inhibited the dephosphorylation of alkylaclglycerol-P and although Mg-2+ (1 mM) appeared to be required for optimal activity, higher levels inhibited the reaction.

Alcohol Oxidoreductases↗
PubMed1975

A method for the quantitative determination of glycerolipids containing O-alkyl and O-alk-1-enyl moieties.

We have developed a spectrophotometric procedure, based on a combination of established methods, for the quantitative determination of aklyl and alk-1-enyl (plasmalogens) ether-linked glycerolipids. It depends upon the release of alkylglycerols and alk-1-enylglycerols from phospholipids by phosphlipase C (Bacillus cereus) followed by saponification or by Vitride reduction the phospholipids; aldehydes are subsequently formed and measured colorimetrically after reacting them with a fuchsin reagent. The total alkyl and alk-1-enyl content of glycerolipids is determined oxidation of the sample withperiodate to form aldehydes and alkylglycolic aldehydes. The O-alk-1-enyl lipid content is determined on a separate sample by measuring the aldehydes produced after acid hydrolysis. The quantity of O-alkyl lipids is calculated from the difference between the values obtained for the total ether-lipid content and that of the O-alk-1enyl lipid content. Alternately, direct determination of alk-1-enylglycerols and alkylglycerols can be made if these hydrolytic products are first separated by thin-layer chromatography.

Animals↗