Hydroxyl Groups Of Glycerol Research Articles

Intra- and inter-molecular hydrogen bonding in diphytanylglycerol phospholipids: an infrared spectroscopic investigation

A series of diphytanylglycerol phospholipids, i.e., diphytanylglycerol phosphate (PA), diphytanylglycerol phosphoglycerophosphate (PGP), the tri- and tetra-methyl derivatives of PGP, and the 2-deoxyglycerol analogue of PGP (dPGP) were studied by Fourier transform infrared spectroscopy. The use of the "deoxy" and methylated analogues of PGP, as well as that of PA and PGP of varying degrees of ionization, allowed the assignment of characteristic infrared bands associated with the phosphate groups. Analysis of these phosphate bands showed that at neutral pH, each of the two phosphate moieties in PGP is singly ionized, whereas in dPGP the phosphomonoester is doubly ionized. This is a consequence of the marked increase in the pK of one of the P-OH groups on the terminal phosphate of PGP (pK > 11), owing to the formation of an intramolecular hydrogen bond between the head group glycerol hydroxyl and the phosphate groups of PGP. Such an intramolecular hydrogen bond can not be formed by the dPGP analogue, and thus both negative charges in dPGP are located at the terminal phosphomonoester group. The O=P—OH groups of PGP also forms a network of intermolecular hydrogen bonds, the exact nature of which depends on concentration and degree of ionization. The possibility of a complex network of hydrogen bonds within (intramolecular) and between (intermolecular) anionic membrane lipids such as that found in PGP, is consistent with the hypothesis that these lipids function as proton-conducting pathways in membranes.Key words: phospholipids, infrared, hydrogen bonding, phosphatidylglycerophosphate, 2-deoxyphosphatidylglycerophosphate.

Transglycosylation and transfer reaction activities of endo-α-N-acetyl-D-galactosaminidase from Diplococcus (Streptococcus) pneumoniae

Abstract Endo-alpha-N-acetyl-D-galactosaminidase from Diplococcus pneumoniae was shown to have transglycosylation and transfer reaction (reversed hydrolysis) activities. Treatment of asialoglycoproteins having Gal beta 1----3GalNAc alpha 1----Ser/Thr linkages with enzyme preparations containing glycerol resulted in formation of nonreducing trisaccharides. The structure of the main trisaccharide (approximately 80%) was deduced to be Gal beta 1----3GalNAc alpha 1----1(3)-glycerol by analysis of sugar composition and the results of exoglycosidase treatment and periodate oxidation. The ability of the endoglycosidase to catalyze transfer of Gal beta 1----3GalNAc to various acceptors was also demonstrated by incubation of the enzyme with the disaccharide and the test compound. The following were found to show acceptor activity: glycerol, Tris, p-nitrophenol, threonine, serine, D-glucose, D-galactose, D-fucose, and 6-O-methylgalactose. Transfer to the primary hydroxyl groups of glycerol and hexoses appears to be favored since the major glycerol product was 1(3)-substituted and transfer to D-fucose and 6-O-methyl-D-galactose was less than that to D-galactose. In order to avoid spurious results, it is necessary to carry out incubations with this enzyme in the absence of glycerol and other hydroxy compounds. The potential use of this endoglycosidase in the synthesis of glycosides is indicated by our studies.

Synthesis and characterization of deoxy analogues of diphytanylglycerol phospholipids

Novel analogues of diphytanyl phospholipids, 2,3-diphytanyl sn-1-glycerol-1-phosphoryl-1′-(1′,3′-propanediol) (dPG), 2,3-diphytanyl- sn-glycerol-1-phosphoryl-1′-propanol (ddPG) and 2,3-diphytanyl- sn-glycerol-1-phosphoryl-1′-(1′,3′-propanediol-3′-phosphate) (dPGP), were synthesized according to modifications of previously published procedures. The samples were TLC and analytically pure and were characterized by 13C- and 1H-NMR and negative FAB/MS. The p K values of dPGP in aqueous dispersions or in methanol/water (1 : 1, v/v) were determined by potentiometric titration and compared with those of 2,3-diphytanyl- sn-glycerol-1-phosphoryl-3′- sn-glycero-1′-phosphate (PGP). The dissociation constant of the third ionizable POH group of dPGP was more than 2 p K units higher than that of PGP, indicating that the free glycerol hydroxyl group plays an important role in headgroup conformation and stabilization, perhaps through hydrogen bonding with the phosphate group(s).

Polar group interaction and molecular packing of membrane lipids: The crystal structure of lysophosphatidylethanolamine

The conformation and molecular packing of 3-palmitoyl- dl-glycerol-1-phosphoryl-ethanolamine has been determined by a single crystal analysis ( R = 0.115); it crystallizes in the monoclinic space group P2 1 a with a unit cell of a = 7.66 A ̊ , b = 9.08 A ̊ , c = 37.08 A ̊ and β = 90.2 ° , with four molecules per unit cell. The molecules exist as configurational and conformational enantiomers and pack in a bilayer arrangement. The phosphorylethanolamine groups have an orientation parallel to the layer surface. The hydrocarbon chains are arranged according to the T∥ chain packing mode and adopt an extreme tilt of 57.5 ° with respect to the layer normal. The free glycerol hydroxyl group forms an intramolecular hydrogen bond with, a phosphate oxygen and thus affects the conformation and orientation of the head group. The phosphorylethanolamine dipoles are oriented parallel to each other in double rows, while they are antiparallel and form a continuous network in dilauroylphosphatidylethanolamine (Elder et al., 1977). The area per molecule in 3-palmitoyl- dl-glycerol-1-phosphorylethanolamine (34.8 Å 2) is less than in diacylphosphatidylethanolamine (38.6 Å 2), indicating that in the latter the hydrocarbon chains determine the molecular cross-section. The significance of the interaction and space requirement of the phosphorylethanolamine group for the phase behaviour of phosphatidylethanolamine is discussed.

Stereospecific distribution of fatty acids in human plasma triglycerides

Because of a biological difference between both primary hydroxylgroups of glycerol there are three distinct hydroxylgroups esterified with fatty acids in triglycerides. The distribution of fatty acids in the three distinct positions of triglycerides can be investigated by a combination of partial hydrolysis of triglycerides by pancreatic lipase, phosphorylation of the diglycerides formed and the stereospecific action of phospholipase A on phosphatides. Plasma triglycerides from normal and hyperlipemic humans are analysed. Human plasma triglycerides are highly asymmetric. The 1-position contains more than twice as much palmitic acid as the 3-position. Statistically significant differences are found between normal and hyperlipemic humans for palmitic and linoleic acid at the 2-position, and for oleic and linoleic acid at the 3-position.

Regulation of lipogenesis in animal tissues.

Publisher Summary This chapter discusses the regulation of lipogenesis in animal tissues. Lipid is an essential component of all living cells, and a large group of lipids contain long-chain fatty acids in their molecules. Among fatty acid-containing lipids, glycerolipids are the most abundant; in them, fatty acids are esterified to glycerol. In triglycerides, the most common glycerolipids, each of the hydroxyl groups of glycerol is esterified to a fatty acid. Triglycerides are the most concentrated store of energy for the organism, yielding per gram over twice as many calories as does carbohydrate or protein. Phosphoglycerides also belong to glycerolipids. The major homeostatic function of lipogenesis is to store as triglycerides the chemical energy of foodstuffs ingested in excess of the immediate energy requirements of the organism. Therefore, the lipogenic process must be precisely regulated in animals in response to their ever-changing energy needs, to the quantity, and the quality of foodstuffs ingested.

The lipid-teichoic acid complex in the cytoplasmic membrane of Streptococcus faecalis N.C.I.B. 8191.

1. A lipid-teichoic acid complex was isolated from Streptococcus faecalis N.C.I.B. 8191. The covalent nature of the linkage between teichoic acid and lipid was established. 2. The complex exhibits macromolecular properties in solution, and ultracentrifugation studies show that these are due to micelle formation. 3. From chemical studies it is concluded that the teichoic acid is a poly(glycerol phosphate) in which some of the glycerol hydroxyl groups possess kojibiosyl [2-O-alpha-d-glucopyranosyl-(1-->2)-alpha-d- glucopyranosyl] substituents, together with d-alanine ester residues. 4. The lipid is 1-kojibiosyl diglyceride, already known as a membrane component of this organism, with probably a phosphatidyl substituent. The phosphatidyl kojibiosyl diglyceride is attached to the teichoic acid through a phosphodiester linkage, and the chain of the teichoic acid contains 28-35 units. 5. Although the complex represents the whole of the membrane teichoic acid in this organism, only about 12% of the membrane glycolipid is associated with teichoic acid. 6. Two phosphatidyl glycolipids, closely resembling that bearing the teichoic acid, were isolated from the lipids of the organism and were partly characterized.

Synthesis of d-ribitol 5-phosphate by an inorganic pyrophosphate-ribitol phosphotransferase activity of microsomal glucose-6-phosphatase

1. 1.Liver microsomal preparations have been shown to catalyze the stereospecific synthesis of a ribitol phosphate from ribitol and inorganic pyrophosphate (PP i). 2. 2.The compound formed has been isolated as a lithium or barium salt and identified as d-ribitol 5-phosphate ( l-ribitol 1-phosphate). Thus the enzyme activity is specific for that primary hydroxyl group of ribitol which corresponds, from the viewpoint of the meso C atom at C-3, to that hydroxyl group of glycerol which is similarly phosphorylated to give glycerol 1-phosphate ( d-α-glycerophosphate). 3. 3.The ribitol phosphate produced from ribitol with ATP and the l-ribulokinase of Aerobacter aerogenes has been identified as d-ribitol 5-phosphate. 4. 4.Glucose is a competitive inhibitor for the synthesis of ribitol phosphate by PP i-ribitol phosphotransferase activity, while ribitol inhibits the synthesis of glucose 6-phosphate non-competitively. 5. 5.The hydrolysis of PP i, which proceeds simultaneously with synthetic phosphotransferase activity, is accelerated by ribitol, as by glycerol, whereas it is inhibited greatly by glucose and slightly by ribose. 6. 6.The four pentitols, under identical conditions, serve as acceptors for phosphotransferase activity from PP i at varying rates: d-arabitol > ribitol > l-arabitol > xylitol . 7. 7.In the livers of fasted and alloxan diabetic rats the levels of enzyme activity are greatly elevated over those found in normal fed animals. In vitro the enzyme is activated by pretreatment of microsomal preparations by NH 4OH or by detergents. These properties, as well as the kinetics of the enzyme reaction, support the conclusion that PP i-ribitol phosphotransferase activity is a property of the same particulate, membrane bound enzyme which is responsible for glucose-6-phosphatase and PP i-glucose (or glycerol) phosphotransferase activities.

The wall teichoic acids of Lactobacillus plantarum N.I.R.D.C106. Location of the phosphodiester groups and separation of the chains.

1. The identities of the component glycerol glucosides of the wall teichoic acids of Lactobacillus plantarum N.I.R.D. C106 have been confirmed by methylation analysis. These glucosides are alpha-d-glucopyranosyl-(1-->1)-l-glycerol, alpha-d-glucopyranosyl-(1-->2)-alpha-d-glucopyranosyl-(1-->1)-l-glycerol and alpha-d-glucopyranosyl-(1-->3)-alpha-d-glucopyranosyl-(1-->1)-l-glycerol. 2. These units are connected by phosphodiester groups attached to the 3(l)-hydroxyl group of glycerol and the 6-hydroxyl group of the non-reducing terminal glucose residues in the adjacent unit. 3. Concanavalin A forms a precipitate with the teichoic acid and the material so precipitated contains only the alpha-d-glucopyranosyl-(1-->2)-alpha-d-glucopyranosyl -(1-->1)-l-glycerol component. This unit is therefore present in a homogeneous polymer so that the teichoic acid is a mixture of this and of other possibly homogeneous chains containing the other two components.

Glyceride studies: Part IX: Intraglyceride distribution of vernolic acid and of five conjugated octadecatrienoic acids in seed glycerides

AbstractVernolic (epoxyoleic) acid, present in six seed oils over the range 19–72%, appears to be preferentially attached to the secondary glycerol hydroxyl group. The distribution of five isomeric conjugated octadecatrienoic acids (8, 10, 12 and 9, 11, 13) in 18 seed oils has been examined by lipase‐catalyzed deacylation. The results are not entirely consistent and more species must be examined before a rational distribution pattern becomes apparent.

Teichoic acids possessing phosphate-sugar linkages in strains of Lactobacillus plantarum.

Cell walls of strains of Lactobacillus plantarum lacking the group D precipitinogen (a glucosylribitol teichoic acid) contain glucosylglycerol teichoic acid in which the glycosidic substituents are attached to the primary hydroxyl group of glycerol. Three distinct repeating units have been isolated from the teichoic acid preparation of strain C106, indicating either that the polymer is complex or that the wall contains a mixture of teichoic acids. Walls of streptobacteria differ from those of L. plantarum and contain neither teichoic acid nor diaminopimelic acid.

On the synthesis of plasmalogens

The chemical synthesis is described of (rac)- trans-1-( n-hexadec-1′-enyloxy)-2-oleoylglycerol-3-phosphorylcholine (plasmalogen). This synthesis made use of a specific degradation of (rac)- trans-1-( n-hexadec-1′-enyloxy)-2,3-dioleoyl glycerol with pancreatic lipase (EC 3.1.1.3). This enzyme, which catalyses the hydrolysis of fatty acid ester bonds attached to the primary hydroxyl groups of glycerol, cannot split vinyl ether linkages, thereby yielding (rac)- trans-1-( n-hexadec-1′-enyloxy)-2-oleoyl glycerol. The latter compound was converted into a plasmalogen by a reaction with 2-bromoethyl-phosphoric acid dichloride and trimethylamine. A partial synthesis of cis-1-( n-alk-1′-enyloxy)-2-oleoyl-glycerol-3-phosphorylcholine was developed by application of this method to cis-1-( n-alk-1′-enyloxy)-2,3-dioleoyl glycerol. The preparation of cis-1-( n-alk-1′-enyloxy)-2,3-dioleoyl glycerol was made by acylation of cis-1-( n-alk-1′-enyloxy)glycerol obtained from ox-heart plasmalogen after degradation with phospholipase C (EC 3.1.4.3) and alkaline hydrolysis. The I.R. spectra of both plasmalogens were completely identical with each other and differed from the spectra of lecithins only by the presence of a vinyl ether absorption at 1660 cm −1. The N.M.R. spectrum of the acetylated synthetic (rac)-1-( n-hexadec-1′-enyloxy)glycerol as well as of the synthetic plasmalogen revealed a trans configuration of the vinyl ether linkage. Degradation with phospholipase A (EC 3.1.1.4) of the synthetic (rac)-plasmalogen gives a 50% conversion into free fatty acid and trans-1-( n-hexadec-1′-enyloxy)glycerol-3-phosphorylcholine while the partial synthetic enantiomeric plasmalogen was converted completely by this enzyme. The same degree of conversion was observed when both plasmalogens were degraded with phospholipase C to (rac)- trans-1-( n-hexadec-1′-enyloxy)-2-oleoyl glycerol respectively cis-1-( n-alk-1′-enyloxy)-2-oleoyl glycerol. When these plasmalogenic diglycerides were incubated with pancreatic lipase no further breakdown was observed indicating the absence of positional isomers. Both plasmalogens could be transformed by phospholipase D (EC 3.1.4.4) into 1-( n-alk-1′-enyloxy)-2-oleoyl-glycerol-3-phosphate. Purified pancreatic lipase did not degrade the plasmalogen.

Formation of galactolipids by chloroplasts

Chloroplasts of higher plants contain relatively large amounts of galactolipids ( Wintermans, 1960). These have been shown to be α, β diglycerides (predominantly dilinolenin), with either one or two D -galactosyl residues attached to the third hydroxyl group of glycerol ( Benson et , al. , 1958 ; Carter et , al. , 1961 ; Sastry and Kates, 1963a). In the present investigation it was found that isolated spinach chloroplasts catalyze the transfer of galactose from UDP- D -galactose-C 14 to an endogenous acceptor, yielding alkali-labile products which are similar, though not identical, to the galactolipids isolated from plant material.

Relative esterifiability of the primary and secondary hydroxyl groups of glycerol

SummaryA method has been devised for determining the relative esterifiability of the primary and secondary hydroxyl groups of glycerol. Contrary to the theory previously advanced by Feuge and Bailey, the primary and secondary hydroxyls are not equally esterifiable. The equilibrium constant favoring esterification of primary hydroxyl over secondary isca. 2.3 at reaction temperature (200°C.) and between 6 and 10 at room temperature. Since the equilibrium constant is substantially different at room temperature from that at reaction temperature, monoglycerides as customarily prepared are not at equilibrium at room temperature and undergo intramolecular migration of acyl groups frombeta toalpha hydroxyl positions. The rate of migration depends on the physical form of the ester and is accelerated by basic catalysts. In the vicinity of room temperature intermolecular rearrangement occurs only over very prolonged periods. The method of calculating relative esterifiability of primary and secondary hydroxyls should be applicable to other polyols.

The Role of Phosphatidic Acid and Phospho-Inositide in Transmembrane Transport Elicited by Acetylcholine and Other Humoral Agents

Publisher Summary This chapter focuses on the group of phosphatides known as “diacyl glycerophosphatides.” The structural feature that all of these compounds share is that they are derivatives of α-glycerophosphoric acid, the two remaining free hydroxyl groups of glycerol being esterified with long-chain fatty acids predominantly of the C 16 and C 18 varieties. The degree of unsaturation of the fatty acids varies with the source of the lipid. Esterification of the phosphate of the phosphatidic acid with any one of a variety of substances, which contain an alcoholic group, gives rise to the other glycerophosphatides. An additional glycerophosphatide—called “diphosphoinositide” because it yields inositol metadiphosphate, glycerol, and fatty acid on acid hydrolysis—is isolated from the brain. Studies on the specific physiological functions of phosphatides in the brain and other organs are discussed in the chapter. Because the phosphatides are important constituents of the cytoplasmic membranes, intracellular organelles, and myelin sheaths, a structural role is assumed as one of their functions. The chapter describes a particular aspect of physiological function in which some phospholipids play an active role. Stimulation of the secretion of sodium chloride, catecholamines, polypeptides, and proteins in a variety of endocrine and exocrine glands is associated specifically with the stimulation of the turnover of phosphatidic acid and phosphoinositide. A similar effect occurs in cholinergic synaptic tissue in response to acetylcholine. The stimulation in synaptic tissue is believed to be associated with the pumping out of sodium that enters the post-synaptic cell body on depolarization by acetylcholine. The various studies suggest that phosphatidic acid functions as a sodium carrier in what has been termed the “phosphatidic acid cycle.”