Effects of double bond configuration on lecithin synthesis

Stearyl‐CoA, oleyl‐CoA and elaidyl‐CoA were prepared and tested as substances in synthesizing lecithin from 1‐ and 2‐acyglycerol‐3‐phosphorylcholine. The rates of acyltransfer were followed by a continuous spectrophotometric assay. The enzyme(s) used to catalyze esterification at the 2‐position did not discriminate appreciably between thecis andtrans isomers of octadecenoate and transferred them more rapidly than the saturated acid, octadecanoate. However, the enzyme(s) which acted at the 1‐position discriminated markedly between the geometric isomers and rapidly transferred totrans‐ octadecenoate and octadecanoate.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142247/1/aocs0465.pd

Quantitative gas chromatography, using retention times

Diffusion of an injected sample within a gas chromatographic column does not begin from a point source but from a band. Therefore the method of calculating relative areas by using retention time × peak height may require a correction factor to give a more accurate estimate of peak areas. When this correction was applied, the analysis was comparable with that obtained by the more time‐consuming triangulation method.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141265/1/lipd0178.pd

FACTORS REGULATING THE BIOSYNTHESIS OF VARIOUS PROSTAGLANDINS

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74636/1/j.1749-6632.1971.tb53190.x.pd

Selective effects of fatty acids upon cell growth and metabolic regulation

Positional isomers ofcis‐methyleneoctadecanoic acid differed greatly in their efficiency for growth of an unsaturated fatty acid auxotroph ofEscherichia coli upon glucose as a carbon source. The 8, 9, and 11 isomers were more efficient in producing cells (60–70 cells/fmole) than the others (0–7 cells/fmole), although all isomers were found esterified to a similar extent into cellular lipid. WithSaccharomyces cerevisiae mutants, all isomers between 6 and 12 supported some growth of the eukaryotic cells, and the 7 and 9 isomers were slightly more efficient than the 8‐isomer. WhenE. coli were grown with glycerol, all isomers from 5 to 14 supported growth, and those with the substituent near the center of the acyl chain had the greatest efficiency (70 cells/fmole). With the glycerol medium, the pattern of efficiencies for the variouscis‐methylene acyl chains resembled the broad selectivity reported earlier for thecis‐ethylenic isomers in glucose medium, which agreed closely with predictions based upon the physical property of their phospholipid derivatives. Thus, metabolism of glycerol appeared to allow the cyclopropane acyl chains to support cell functions to the limits expected for bulk phase chain‐chain fluidity considerations. This broad specificity was also obtained when cells were grown on glucose with cyclic AMP added to the culture. Therefore, the selective inadequacies of the 5, 6, 7, 10, 12 and 13 isomers in supporting cell growth on glucose may occur through an interaction modified by cAMP and dependent upon reduced cellular levels of cyclic AMP. The highly selective pattern of efficiency of thecis‐methylene acids forE. coli growth on glucose resembles that with the acetylenic acids, but was shifted one carbon atom toward the methyl terminus. This observed selectivity pattern seems due to interactions of the individual acyl chains with cellular protein(s) rather than to chain‐chain interactions in a bulk phase. The ability of certain positional isomers to support cell function equally well in both nutrient conditions suggests that the role of those acyl chain isomers may be independent of metabolite flux or cyclic nucleotide contents of the cell, whereas the actions of other isomeric fatty acids seem closely related to the metabolic status of the cell. A highly selective role for different fatty acids in modulating cellular function seems possible on the basis of the current evidence.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141577/1/lipd0878.pd

A comparison of acyltransferase activities in vitro with the distribution of fatty acids in lecithins and triglycerides in vivo

The location and configuration of a double bond in a fatty acid influences the rate of its acyltransferase‐catalyzed esterification to form lecithin and its distribution in vivo between the primary and secondary positions of triglycerides and lecithins.Saturated acids of shorter chain length are transferred at rates similar to the long chain unsaturated acids.The positional distributions of acids in the diglyceride units of liver triglycerides appear to be similar to that found in the lecithins.Acyltransferase activities measured in vitro have a considerable predictive value in terms of the ultimate distribution of fatty acids in glycerolipids in vivo.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141483/1/lipd0224.pd

The incorporation of14C‐glycerol into different species of diglycerides and triglycerides in rat liver slices

The relative rates of de novo synthesis of species of diglycerides and triglycerides from14C‐glycerol were examined in rat liver slices. Diglycerides containing one or two double bonds per molecule and triglycerides containing four or more double bonds per molecule represented 70% and 60% respectively of the newly synthesized diglycerides and triglycerides. The newly synthesized triglycerides were more unsaturated than the endogenous triglycerides. Our results suggest that a nonrandom synthesis of species of diglycerides occurred followed by an almost random utilization of the various diglyceride species for the biosynthesis of triglycerides.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142207/1/lipd0411.pd

Evidence for an activating factor formed during prostaglandin biosynthesis

SummaryThe oxygenation of 5,8,11,14-eicosatetraenoic acid by acetone powder preparations of sheep vesicular glands proceeded with a lag or accelerative phase when inhibitory concentrations of NaCN were present. This accelerative feature of the reaction suggested that an activating material might be produced as the oxygenation reaction proceeds. When a second addition of fresh enzyme was made to a reaction mixture, the lag phase was as short as in uninhibited controls. This indicated that an activating factor was required for optimal activity of this dioxygenase, and that it accumulated during the oxygenation reaction in the presence of NaCN. The factor was extracted from an aqueous incubation medium with cold diethyl ether. There was a positive relationship between the amount of activating factor added and the resultant increase in the initial velocity of the oxygenation system.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22023/1/0000439.pd

The Subcellular Distribution of Acyltransferases which Catalyze the Synthesis of Phosphoglycerides

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65213/1/j.1432-1033.1969.tb00602.x.pd

Quantitative effects of unsaturated fatty acids in microbial mutants : VII. Influence of the acetylenic bond location on the effectiveness of acyl chains

The ability of a series of 18 carbon acetylenic fatty acids to fulfill the unsaturated fatty acid requirements of Escherichia coli and Saccharomyces cerevisiae was investigated. Despite their high melting points (>40[deg]C), several isomers of the acetylenic fatty acids were as efficient or more efficient in supporting growth than the analogous fatty acid having a cis-double bond.The efficiencies of the different positional isomers in supporting cell proliferation varied from essentially 0 cells per fmol for the 2-5 and 13-17 isomers to high values when the acetylenic bond was near the center of the chain: e.g. 45 E. coli and 5.5 S. cerevisiae cells/fmol for the 10 isomer. A striking ineffectiveness of the 9 isomer was observed with E. coli. The 7, 8 and 10 isomers were at least 10-fold more efficient than any of the other positional isomers in supporting the growth of E. coli. In contrast, the 9 isomer was among the most effective acetylenic fatty acids tested with the yeast mutant.Chromatographic analysis of the extracted lipids indicated that each of the acetylenic isomers tested (except [Delta]2 and [Delta]3) could be esterified by the prokaryotic and eukaryotic microorganisms. The content of unsaturated plus cyclopropane acids observed when growth ceased in E. coli cultures supplemented with growth-limiting concentrations of the acetylenic fatty acids ranged from approx. 15 mol% for the 8 isomer to approx. 35 mol% for the 14 and 17 isomers. The 8-11 isomers were observed to be esterified predominantly at the two position in phosphatidylethanolamine of E. coli and in phosphatidylcholine of S. cerevisiae.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22954/1/0000521.pd

Intracellular Phospholipase A1 and Acyltransferase, Which Are Involved in Caenorhabditis elegans Stem Cell Divisions, Determine the sn-1 Fatty Acyl Chain of Phosphatidylinositol

Phosphatidylinositol (PI) is unique in the abundance of stearic acid at the sn-1 position. This fatty acid is thought to be incorporated through fatty acid remodeling. Here, we identified a phospholipase and acyltransferases involved in the fatty acid remodeling at the sn-1 position of PI and provide a link between the sn-1 fatty acid of PI and asymmetric cell division