Biomedical subjects

M Kates

Publications and source records attributed to M Kates.

At least 91 records · Page 5Linked to original sources

PubMed1976

Nonpolar lipids of a halotolerant species of Staphylococcus epidermidis.

The nonpolar lipids of a halotolerant Staphylococcus epidermidis, isolated in pure culture from a growth medium for extreme halophiles containing 25% sodium chloride, were found to contain squalene, menaquinone-7, free fatty acids (mainly anteiso-15:0 and anteiso-17:0), undecaprenol, nonaprenol with predominately cis-isoprene residues, heptaprenol, with predominately trans-isoprene residues, and 1,2- and 1,3-diglycerides containing anteiso- 15:0 and anteiso-17:0 branched chain fatty acid residues. The above compounds were isolated in pure form by column and thin-layer chromatography and were characterized by ultraviolet, proton magnetic resonance, and mass spectra. Fatty acid moieities were characterized by gas-liquid chromatographic retention times of their methyl esters.

Chromatography, Thin Layer↗

PubMed1976

Enzymatic synthesis of C40 carotenes by cell-free preparation from Halobacterium cutirubrum.

[14C]Mevalonate or (14C)isopentenyl pyrophosphate was found to be converted to transphytoene, trans-phytofluene, lycopene, and beta-carotene by a cell-free 270 000 X g supernatant fraction prepared from Halobacterium cutirubrum cells that were broken by manual grinding with glass beads. Incubations were done under N2 in the dark at 37 degrees C in 4 M NaCl in presence of FAD, NADP, and MgCl2; ATP was also added when mevalonate was the substrate. This system was also capable of converting trans-(14C)phytoene to beta-carotene via the intermediates trans-phytofluene, zeta-carotene, neurosporene, lycopene, and gamma-carotene. Each of these labelled intermediates on incubation separately with the same enzyme system was shown to be converted to the intermediates farther down the pathway. The results of this study show that the biosynthetic pathway for the formation of C40 carotenes in H. cutirubrum proceeds as follows: isopentenyl pyrophosphate leads to trans-phytoene leads to trans-phytofluene leads to zeta-carotene leads to neurosporene leads to lycopene leads to gamma-carotene leads to beta-carotene. This pathway differs from that in higher plants in that the cis isomers of phytoene and phytofluene are not on the main pathway of carotene biosynthesis, as they are in higher plants. Furthermore, trans-phytoene, which has not been reported to have any role in higher plants, appears to be the main intermediate in carotene biosynthesis in H. cutirubrum.

Carotenoids↗

PubMed1976

Effect of nicotine on biosynthesis of C50 carotenoids in Halobacterium cutirubrum.

The major carotenoids in pigmented extreme halophiles are the hydroxylated C50 red pigments bacterioruberin (major, 84%) and monoanhydrobacterioruberin (minor, 14%). When cells of Halobacterium cutirubrum were grown in the presence of nicotine they accumulated lycopene and bisanhydrobacterioruberin; maximal accumulation (80% lycopene, 20% bisanhydrobacterioruberin) occurred at 3mM nicotine. Removal of nicotine resulted in the reformation of monoanhydrobacterioruberin and bacterioruberin at the expense of lycopene and bisanhydrobacterioruberin. Thus nicotine does not inhibit the addition of the two extra isoprene units plus two hydroxyl groups (at C1 and C1') to a C40 carotenoid skeleton. It does, however, inhibit the hydration steps at C3'' and C3''' that convert bisanhydrobacterioruberin to monoanhydrobacterioruberin and finally bacterioruberin. These results support the view that the C50 carotenoids can be formed from a C40 carotene, lycopene.

Carotenoids↗

PubMed1975

A novel sulfonolipid in diatoms.

A new sulfonolipid has been isolated from a non-photosynthetic diatom, Nitzschia alba, by thin-layer and column chromatography on silicic acid, and characterized by 35S-labeling, mobility on thin-layer chromatography, infrared and NMR spectroscopy and products of hydrolysis, as a ceramide sulfonic acid (N-acyl sphingosine-1-sulfonic acid). The long-chain base moiety was shown by identification of the products of periodate or periodate-permanganate oxidation to consist of a C18-trans-sphingosine backbone linked directly by a C-S linkage through C1 to a SO3 group. The N-acyl groups were mainly isoheptadecanoic (64%) and palmitic (26%) acids.

Ceramides↗

PubMed1975

The lipid composition of a halotolerant species of Staphylococcus epidermidis.

Studies were carried out on the lipid composition of a halotolerant Staphylococcus epidermidis isolated in pure culture from a growth medium for extreme halophiles containing 25% NaCl. The four major polar lipid components in this bacterium were found to be: (a) glycerophosphoryl diglucosyl diglyceride (10% by weight) with structure 3(1)-O-(-sn-glycerol-1-phosphoryl-6'-O=(beta-D glucopyranosyl-(1 leads to 6)- O-beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol; (b) diglucosyl diglyceride (15% by weight) with structure 3(1)-O-(beta-D-glucopyranosyl (1 leads to 6)-O-beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol; (c) monoglucosyl diglyceride (3% by weight) with structure 3(1)-O-(beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol, and (d) phosphatidylglycerol (60% by weight) with structure 1,2 diacyl-sn-glycero-3-phosphoryl-1'-sn-glycerol. Phosphatidic acid, cardiolipin, lysophosphatidylglycerol and three unidentified phospholipids were also detected in small amounts. Each lipid component had essentially the same fatty acid composition namely, anteiso-15:0 (60-75%), anteiso-17:0 (18-24%), iso-17:0 (8--10%), and small amounts of palmitic and stearic acids (2-5%). The fatty acids were non-randomly distributed in phosphatidylglycerol, the shorter chain anteiso 15:0 fatty acid being exclusively esterified to the 2-position and the longer chain anteiso- and iso-17:0 fatty acids at the 1-position. The fatty acid composition was not affected by increaseing NaCl content in the medium in the rande 0--15% but the proportion of anteiso-15:0 increased greatly when the salt concentration was increased to 25%. The proportions of ionic polar lipids were modified to give an increased net negative charge per mol ionic lipids when NaCl in the medium was increased from 15 to 25%, but the proportions of neutral glycolipids remained fairly constant.

Cardiolipins↗

PubMed1975

Isolation and characterization of C50-carotenoid pigments and other polar isoprenoids from Halobacterium cutirubrum.

The polar acetone-soluble lipids of Halobacterium cutirubrum were found to contain (in addition to the previously reported vitamin MK-8 and retinal) neo-bacterioruberin U, bacterioruberin, monoanhydrobacterioruberin, bis-anhydrobacterioruberin, an isomer of geranylgeraniol (with one internal cis-isoprene residue), 2,3,-di-O-phytanyl-sn-glycerol and two unidentified polar isoprenoids. All compounds were isolated in pure form by column and thin-layer chromatography, quantitated and characterized by their visible, ultraviolet, infrared, proton magnetic resonance and mass spectra and the spectra of their acetyl or silyl derivatives and/or dehydrated products.

Carotenoids↗

PubMed1975

Characterization of a membrane-bound phospholipid desaturase system of candida lipolytica.

Several characteristics of the microsomal phospholipid desaturase of Candida lipolytica are described. The phospholipid desaturase reaction required molecular oxygen and reduced pyridine nucleotides as essential cofactors and was inhibited by cyanide but not by carbonmonoxide, indicating that it required cytochrome b5. Desaturation of both 1-acyl-2-[14-C]oleoyl-sn-glycero-3-phosphorylcholine and 1,2-di-[14C] oleoyl-sn-glycero-3-phosphorylcholine appeared to follow Michaelis-Menten kinetics, with apparent Km values of 2.5 10-minus 4 M and 9.5 10-minus 4 M, respectively. Desaturation of the di-[14C] oleoylphosphatidylcholine took place at both position-1 and position-2; the distearoyl or dielaidoyl phosphatidylcholines were not desaturated. Rate of desaturation of the 1=acyl-2-[14-C] oleoyl-glycerophosphorylcholine by microsomes from cold-grown cells was equal to or slightly less than that by microsomes from cells grown at the normal growth temperature of 25 degreesC, measured in the temperature range 10-30 degrees C. However, the rate of desaturation of [14-C]-oleoyl-CoA desaturase was greater with the microsomal preparation from cold-grown cells than with that from 25 degreesC grown cells. These data suggest that the observed increase of diunsaturated fatty acids in cold-grown cells may perhaps be explained by the increased activity of the oleoyl-CoA desaturase acting at the low temperature.

Candida↗

PubMed1975

Isolation and characterization of Actinopolyspora halophila, gen. et sp. nov., an extremely halophilic actinomycete.

An actinomycete, isolated as a contaminant of a culture medium containing 25% NaCl, has been classified as Actinopolyspora halophila gen. et sp. nov. in the family Nocardiaceae. The morphology and biochemical characteristics of this organism distinguish it from other members of the family Nocardiaceae and other genera possessing a type IV cell wall. It requires high NaCl concentrations for growth and can grow in saturated NaCl. The lowest concentration permitting growth in liquid medium is 12%, and on solid medium, 10%. Colonies developing at lower salt concentrations contain holes resembling viral plaques. No growth occurred in a medium containing 30% KCl instead of NaCl. This organism can grow in simple media with NH4+ salts as nitrogen source and different sugars and other compounds as carbon source. Though it has a salt requirement almost as great as the extremely halophilic rods and cocci, it differs from these in containing diaminopimelic acid and in sensitivity to lysozyme; both properties suggest that it has a mucopeptide cell wall. It also contains some phospholipids common to other actinomycetes, but does not contain any phytanyl ether linked lipids characteristic of other extremely halophilic bacteria.

Cell Wall↗

PubMed1975

Characterization and composition of the purple and red membrane from Halobacterium cutirubrum;.

The purple membrance (bacteriorhodopsin) isolated from cells of Halobacterium cutirubrum grown anaerobically in the light was shown to contain 77% protein and 20% lipils by weight. The protein component consisted of a single protein moeity, having a molecular weight of (19.6 plus or minus 0.8) times 10-3, complexed with retinal in mole ratio of 2:1, respectively. The protein moeity is not glycosylated but may be phosphorylated (ca. 2 mol of phosphate per mole of protein). The red membrance contains 56%protein and 38% lipids, including bacterioruberins. Several polypeptide components are present including some which may be glycosylated and/or phosphorylated. The lipids of both membranes contained phosphatidyl glycerophosphate (52%) and phosphatidyl glycerol (3-4%) but the sulfated lipid components, glycolipid sulfate and phosphatidyl glycerosulfate, were present exclusively in the purple membrane, the red membrane containing instead two unidentified glycolipids. Neutral lipids (squalenes, vitamin 75-8, etc.) were present in both membranes to the extent of 7-9%.

Amino Acids↗

PubMed1975

A simplified procedure for synthesis of di-[14C]acyl-labeled lecithins.

A simplified procedure for synthesis of 1,2-di-[1'-14C]oleoyl-, 1,2-di-[1'-14C]linoleoyl-, and 1,2-di-[1'-14C]eicosatrienoyl-sn-glycero-3-phosphorylcholine is described. The method involves acylation of the CdCl2 complex of glycerophosphorylcholine with a 14C-labeled fatty acid in the presence of trifluoracetic anhydride and pyridine. The 14C-labeled lecithin is isolated in pure form by preparative thin-layer chromatography and alumina column chromatography in an overall yield of 12-24%. No isomerization or peroxidation of the unsaturated acids was detected.

Carbon Radioisotopes↗

PubMed1974