Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Diglycerides”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed1975

Biosynthesis and structure of glycosyl diglycerides, steryl glucosides, and acylated steryl glucosides.

A particulate enzyme fraction from Mycobacterim smegmatis catalyzed the transfer of -14C-glucose from the UDP--14C-glucose into neutral glycolipids. The two major radioactive components were purified by column chromatography on O-diethylamino ethyl cellulose (acetate) and thin layer chromatography on silica gel in several solvents. The first product yielded a water-soluble component upon saponification, which had a hexoseglycerol ratio of 1:1 with all of the hexose being identified as glucose. The second product yielded a water-soluble component upon saponification which contained hexose and glycerol in a 2:1 ratio and, in addition to glucose, contained lesser amounts of mannose and galactose. Palmitate and oleate were the predominant fatty acids and were present in equimolar amounts. The products thus have been identified as monoglycosyldiglyceride and diglycosyldiglyceride. The diglycosyldiglyceride could also be labeled with -14C-galactose when UDP--14C-galactose served as the donor, but the monoglycosyldiglyceride was only slightly labeled with -14C-galactose. Membrane fractions from mung bean seedlings catalyzed the transfer of -14C-glucose from UDP--14C-glucose into a neutral glycolipid which has been purified by thin layer chromatography and analyzed by combined gas liquid chromatography-mass spectrometry. It was determined to be a steryl glucoside with the two major sterol components being betasitosterol and stigmasterol linked to beta-D-glucose. Particulate fractions from developing cotton fibers also catalyzed the formation of steryl glucosides and, in addition, they catalyzed the esterification of steryl glucosides at the 6 position of glucose with fatty acids (primarily palmitate and oleate) from an andogenous acyl donor. Both the glucosyl transferase and the acyltransferase have been solubilized with Triton X-100 and partially purified by chromatography on Sephadex G-200. The acyltransferase activity was reconstituted by the addition of the steryl glucoside and a phospholipid acyl donor.

Acyltransferases↗
PubMed1975

Biosynthesis of galactosyl diglycerides by non-green fractions from chloroplasts.

When either mitochondria, chloroplast stroma lamellae, or osmotically shocked chloroplasts were centrifuged through sucrose gradients, zones were always obtained at the 0.6 M-0.9 M boundary which were highly active in galactosyltransferase. These activities did not coincide with maxima for chlorophyll or cytochrome c oxidase activity. A second chlorophyll-free fraction was obtained at lower density, showing high galactosyltransferase activity when incubated after isolation. The results indicate that the highly active fractions originate from chloroplast envelopes.

Cell Fractionation↗
PubMed1984

Rapid diglyceride phosphorylation in isolated bovine rod outer segments.

When isolated bovine rod outer segment fragments were incubated with [gamma-32P]ATP, 32P, as revealed by autoradiography, was rapidly incorporated into rhodopsin bands on sodium dodecyl sulfate polyacrylamide gels, and into a low Mr lipid band. Incorporation of 32P into rhodopsin was light-dependent, but labeling of the lipid band was not. A single phosphorylated product, phosphatidic acid, was identified by 2-dimensional thin layer chromatography and by high pressure liquid chromatography of the corresponding glycerophosphate ester. Incorporation of label into phosphatidic acid was detected as early as 15 sec following start of incubation and the product was stable for at least 30 min. No other products were detected, indicating that under the experimental conditions phosphatidic acid was not metabolized to other phospholipids. Up to 1 mol phosphatidic acid was formed per 18 to 40 mol rhodopsin present.

Adenosine Triphosphate↗
PubMed1989

Mass determination of receptor-mediated accumulation of phosphatidate and diglycerides in human neutrophils measured by Coomassie blue staining and densitometry.

Quantitation of 1,2-diacylglycerol (AAG), 1-0-alkyl-2-acylglycerol (EAG) and phosphatidic acid (PA) was conducted in polymorphonuclear leukocytes (PMN) labeled with 1-0-[3H]alkyl-2-acyl-GPC following stimulation with 1 microM fMLP using Coomassie blue staining and densitometry. At 5s AAG and PA increased by 80% and 107%, respectively, over controls. The accumulation of PA, which reached a maximum by 30s, was higher than AAG by 302% at 5s, and 550% at 30s. EAG accumulation was delayed by 15s following stimulation of PMN. These results show that AAG accumulates before EAG and support the role of AAG in cellular activation, perhaps, via the stimulation of protein kinase C (PKC). EAG may serve to counter the effects of AAG or may itself elicit responses. The high concentrations of PA which accumulate early suggest that PA may be generated by the activation of phospholipase D in PMN stimulated with fMLP.

Chromatography, Thin Layer↗
PubMed1990

A new approach to determine the stereospecificity in lipase catalysed hydrolysis using circular dichroism (CD): lipases produce optically active diglycerides from achiral triglycerides.

We describe a sensitive CD method for determining the stereospecificity in lipase (E.C.3.1.1.3) catalysed hydrolysis of triacyl glycerols into diacyl glycerols. The diglycerols were converted to chiral tert-butyldimethylsilylated 1,2- or 2,3-di-O-benzoyl-sn-glycerol (5 or 5'), and their CD was measured. This approach showed for the first time that lipases produce optically active diacyl glycerides from achiral tripalmitin and tribenzoyl glyceride with a variable extent of enantioselectivity depending on the acyl groups and the enzymes.

Benzyl Alcohols↗
PubMed1986

Membrane protein-lipid hydrogen bonding: evidence from protein kinase C, diglyceride, and tumor promotors.

Membrane-bound proteins owe their retention and conformation in the lipid bilayer to hydrophobic peptide domains. Additional fixation, by protein-lipid hydrogen bonding, has been suggested, and recent reports on protein kinase C activation by diacylglycerol (DG) provide an unambiguous model for such bonding. The sn-1,2-diacylglycerol appears to donate a hydrogen bond from the sn-3 hydroxyl to the enzyme and to receive two hydrogen bonds, in the sn-1 and sn-2 ester CO groups, from the enzyme. This arrangement is confirmed in phorbol ester, a competitive inhibitor of DG for the kinase. This tumor promotor has a nearly identical spatial arrangement of hydrogen bond donor (9 alpha-OH) and acceptors (12 and 13 ester CO); so have two other tumor promotors, teleocidin and aplysiatoxin. There are reasons to believe that protein kinase C is not the only protein that is bound to membrane lipids by hydrogen bonding, and such bonding will have to be considered in membrane-associated events such as fusion, cross-membrane transport, or anesthesia.

Carcinogens↗
PubMed1994

The transit sequence of a chloroplast precursor protein reorients the lipids in monogalactosyl diglyceride containing bilayers.

The interaction of the chloroplast precursor protein of ferredoxin with mixed model membranes composed of 2H chain labeled monogalactosyl diacylglycerol and phosphatidylcholine was studied by 2H and 31P NMR. The bilayers were found to have special chain packing properties which most likely are the result of a specific arrangement of head groups at the interface. The precursor and not the corresponding apoprotein induced a bilayer-->isotropic transition in lipid organization as a result of the transit sequence-lipid interaction. The implications of these observations for proteins import into chloroplasts are indicated.

Biological Transport, Active↗