M. Kates

Lipid components of diatoms

Abstract 1. 1. The total lipids of five species of marine diatoms and one fresh-water diatom were studied chromatographically and the major components identified. All species contained glycerides, sulfoquinovosyl diglyceride, digalactosyl diglyceride, monogalactosyl diglyceride, phosphatidyl glycerol, lecithin, and phosphatidyl inositol as major lipid components. Small to trace amounts of several unidentified sulfur-con-taining lipids, an unidentified glycolipid (sphingolipid?), phosphatidyl ethanolamine, phosphatidyl-N-methylethanolamine, phosphatidic acid, and diphosphatidyl glycerol were also present. In general, the lipid composition of the diatoms resembled that of green algae. 2. 2. Data on 32P-, 14C-, and 35S-incorporation into the diatom lipids are also included in this study. 3. 3. The major fatty acid constituents in the total lipids of the diatoms examined were palmitoleic, palmitic, eicosapentaenoic, and eicosatetraenoic acids ; small amounts of hexadecadienoic, hexadecatrienoic, octadecenoic, octadecadienoic, and octadecatrienoic acids were also present. The latter acid (linolenic acid), which is the major acid in algae and higher plants, was only a minor constituent of the diatom lipids.

A DIETHER ANALOG OF PHOSPHATIDYL GLYCEROPHOSPHATE IN HALOBACTERIUM CUTIRUBRUM.

Abstract 1. 1. The major phosphatide in the extremely halophilic bacterium, Halobacterium cutirubrum , has been isolated by a combination of solvent fractionation, precipitation through the barium salt, and final purification as the sodium salt. 2. 2. Analytical and degradative data showed the phosphatide to be a phosphatidyl glycerophosphate with two long-chain ether groups instead of fatty acid ester groups. 3. 3. Both long-chain groups were found to be identical and were shown by comparison of infrared, nuclear magnetic resonance, and mass spectra with those of dihydrophytyl derivatives to have the structure 3,7,11,15-tetramethylhexadecyl. The two long-chain groups are joined by ether linkages to the α, β-positions of l -glycerol. 4. 4. The structure proposed for the major phosphatide in H. cutirubrum is therefore :2,3- di -0-[3′,7′,11′,15′-tetramethylhexadecyl]-glyceryl-1-phosphoryl-[1Prime;(3Prime;)-glyceryl-3Prime;(1Prime;)-phosphate], in the notation of Hirschmann. 5. 5. Possible biochemical and physiological functions of this unusual phosphatide in the halophile cell are discussed.

Lipids of influenza virus and their relation to those of the host cell

Abstract Influenza virus was propagated in chick embryo and in calf-kidney cells. The lipids of the purified virus were found to resemble closely those of the particular host cell in which they were grown. When the virus was propagated in the presence of unlabelled medium in calf-kidney cells which had previously been labelled with 32 P, the lecithin, sphingomyelin, phosphatidyl ethanolamine, phosphatidyl inositol, and phosphatidyl serine components of the virus lipids had specific activities almost identical with those of the corresponding components in the uninfected host cell. However, the phosphatidic acid component of the virus had a much lower specific activity and a much higher concentration than that of the uninfected host cell. Apparently, the virus incorporates lipid components present in the host cell before infection, together with those components ( e.g. phosphatidic acid) newly synthesized by the infected (damaged) host cells. It is concluded that the virus does not specifically direct lipid synthesis in the host cell, as it does nucleic acid and protein synthesis.

Chromatographic and radioisotpic investigations of the lipid components of runner bean leaves

Abstract The total lipids of runner bean leaves have been separated by chromatography on silicic acid-impregnated paper into at least eleven components. These have been partially identified by their R f values, staining behaviour with various specific reagents, radioisotope incorporation data, and products of milk alkaline hydrolysis. Apart from pigments and glycerides, six phosphatide components were found, five of which have been identified as lecithin, phosphatidyl ethanolamine, phosphatidyl glycerol, phosphatidyl inositol and phosphatidic acid; also, four distinct glycolipids, and a sulfur-containing lipid were detected. Hydrolysis studies showed that the four glycolipids contained galactose, glucose, glycerol and an unknown sugar in different molecular proportions, and that the sulfolipid contained glucose, the same unknown sugar, and an acid-stable form of sulfur.

Phosphatides of human blood cells and their role in spherocytosis.

Abstract Spherocytes were found to contain a higher surface concentration of phosphatides than normal cells, but no limitation of overall phosphatide synthesis or turnover, and no significant variation from normal of fatty acid or long chain aldehyde composition was observed. However, the phosphatides of spherocytic cells were found to contain a significantly lower proportion of phosphatidyl ethanolamine and a correspondingly higher proportion of lysophosphatidyl ethanolamine. The latter component when added to normal serum was observed to produce sphering of normal red cells. It is concluded that the primary genetically controlled abnormality in hereditary spherocytosis probably lies in a partial block in the enzymic system for conversion of lysophosphatidyl ethanolamine to phosphatidyl ethanolamine. All other observed differences between normal and spherocytic cells could be secondary to such a defect.

SYNTHESIS OF THE NATURALLY OCCURRING PHYTANYL DIETHER ANALOGS OF PHOSPHATIDYL GLYCEROPHOSPHATE AND PHOSPHATIDYL GLYCEROL

Abstract The diastereomers of the diphytanyl glycerol ether analogs of phosphatidyl glycerophosphate and phosphatidyl glycerol have been synthesized chemically and compared with the respective natural isomer isolated from the extremely halophilic bacterium, Halobacterium cutirubrum. The structure and configuration of the natural isomer of the phosphatidyl glycerophosphate was thus shown to be 2,3-di-O-(3′R,7′R, 11′R,15-tetramethylhexadecyl)-sn-glycero-1-phosphoryl-3″-sn-glycero-1″-phosphate (XVb); the natural phosphatidyl glycerol was shown to have the structure and configuration, 2,3-di-O-(3′R,7′R,11′R,15-tetramethylhexadecyl)-sn-glycero-1-phosphoryl-3″-sn-glycerol(XVIIIb). The implications of these findings on the biosynthetic mechanisms for these unusual phosphatides are discussed.

Phosphatide components of fowl blood cells.

The phosphatide components of fowl blood cells were separated by chromatography on silicic acid-impregnated paper and found to consist of lecithin (42%), phosphatidyl ethanolamine (24%), sphingomyelin + lysophosphatidyl ethanolamine (21%), and small amounts of phosphatidyl serine, lysolecithin, phosphatidyl inositol and phosphatidic acid. Each component had a different fatty acid composition; in particular, phosphatidyl ethanolamine had a higher proportion of polyunsaturated fatty acids and of stearic acid, and a lower proportion of palmitic acid than lecithin. These two phosphatides were also present in their respective plasmogen forms, the aldehyde moieties of which were found to be mainly palmitaldehyde and stearaldehyde. n nIncubation of the total blood cells with [2−14]acetate resulted in the incorporateion of 14C into the non-phosphatide fraction (cholesteryl esters, cholesterol and diglycerides) and to a lesser extent into the lecithin, phosphatidyl ethanolamine and sphingomyelin components.