Glycerol-2-phosphoric acid

All phosphoglycerides are derived from j -glycerol-3-phosphoric acid in which the phosphoric acid moiety is esterified with certain alcohols and the hydroxyl groups on C-l and C-2 are esterified with fatty acids. 

Question In what form will s -glycerol-3-phosphoric acid exist at physiological pH ... 

Fig. 3-18 Glycerol 3-phosphoric acid (left) and phosphoglyceride (general structure right).

The a isomer, glycerol-3-phosphoric acid, contains an asymmetric carbon atom and is optically active. When prepared by ordinary chemical methods, a racemic mixture is obtained bnt a single optically active isomer is usually produced in biochemical reactions. The natural product isolated from animal and vegetable phosphatides (Chapter 10.3) contains approximately three parts of P to one part of optically active a. 

Hydrolysis. The first effect of either acid hydrolysis or alkaline hydrolysis (saponification) is the removal of the fatty acids. The saponification value of commercial lecithin is 196. Further decomposition into glycerol, phosphoric acid, and head groups (ie, choline, ethanolamine, etc) may foUow prolonged heating. Lecithin may also be hydrolyzed by enzymes. 

Glycerol is used (l) in the manufacture of high explosives, e.g,. glyceryl trinitrate ( nitroglycerin ), which is the main component of dynamite. (2) in antifreeze solutions, especially for automobile radiators. (3) to maintain a moisi condition in fruits and tobacco, (4) in cosmetics and skin preparations, and (5) to prepare glycerol phosphoric acid, used in medicine, and "boroglyceride" used as, a preservative. See Table l... 

FAB-MS spectral pattern. This potent technique is most effective as an aid in structure proof of lipid (glycerol) phosphoric acids. These compounds produce a protonated molecule [MH]+ as well as several other ions of importance. Analysis of an alkyl (16 0) lysoGPA will show an ion at m/z 397, which is attributed to the [MH]+. If an acyl (16 0) lysoGPA is examined by FAB-MS, an ion is found at m/z 411, which is indicative of its [MH] +. Another important ion is [MH-H3P04]+, m/z 313 (acyl (16 0) lysoGPA), and m/z, 299 (alkyl 16 0) lysoGPA). Further information on the FAB-MS patterns of these and other phosphoric acid derivatives is summarized in a recent publication by Sugiura et al. (1994). 

Phosphoglycerides—Products formed from the reaction of glycerol, phosphoric acid, and fatty acids. 

Complex (or polar) lipids give three or more products, such as fatty acids, glycerol, phosphoric acid, and an organic base. Typical complex lipids include the glycer-ophospholipids (phospholipids), glycoglycerohpids (ga-lactolipids), and the sphingolipids. A natural lipid mixture comprises different types (denoted as lipid classes) of simple and complex lipids. 

Phosphatidylcholine can be completely hydrolysed with aqueous acid to produce fatty acids, glycerol, phosphoric acid and choline. With alkali, the fatty esters are preferentially hydrolysed, leaving the glycero-phosphoryl-cholines, which can in turn hydrolyse slowly into glycerophosphoric acid and choline. Enzymatic hydrolysis occurs selectively at different ester sites by several phospholipases to produce a range of products. Phospholipases A1 and A2 are obtained commercially from snake venom. They hydrolyse the fatty acid at the -1 and sn-2 positions respectively, to produce lysophosphatidyl-choline. Phospholipase C catalyses the hydrolysis of the phosphate moiety to give 1,2-diacylglycerols and phosphorylcholine. Phospholipase D found in plant tissues mainly catalyses hydrolysis of the phosphate ester to produce choline and phosphatidic acids (1). 

PC, a major class of phospholipids which are important components of the membrane lipids in animals and plants. They are zwitterionic and contain, in bound form, glycerol, phosphoric acid, fatty acids (2 moles) and choline. A major component of crude lecithin from soybean and other vegetable oils. 

Most phospholipids contain glycerol, phosphoric acid, a short-chain hydroxy-compound, and long-chain acids or alcohols. Minor variants of this pattern and new ways of associating these components continue to be identified, as for example the phosphatidyl-AT-(2-hydroxyethyl)alanine (16) from rumen protozoa. ... 

The enzymatic hydrolysis of lecithin to fatty acids, glycerol, phosphoric acid, and choline requires the participation of some four enzymes. The enzymes attacking the various bonds of a lecithin molecule are summarized in Table XIV. The bonds which are cleaved are referred to by number in the lecithin formula shown below the same numbers are used in Table XIV to indicate the respective enzymes involved. The cleavage of the fatty acid-glycerol bond, as represented by diagonal lines 1 and 2, is based on hydrolysis studies of simple esters. Diagonal lines 3 and 4 are only provisional, as presumably either a P—0 or C—O bond to phosphate could be cleaved. 

Glycerophospholipid (Section 27.3) A lipid that contains a glycerol backbone linked to two fatty acids and a phosphoric acid. 

Phosphatidic acid is glycerol esterified at the sn-1 and sn-2 positions to two fatty acids and at the sn-3 position to phosphoric acid. It is a product of phospholipase D action that is also an intermediate in the biosynthesis of phosphatidylseiine and phosphatidylinositol. 

Preparation. A continuous process is described in Ref 26 for its prepn from nitric acid and acetylene. Other prepns on both lab and industrial scales are by the action on Tetranitro-methane (TeNMe) of K hydroxide in aq glycerol (Ref 16), aq HOCHjSOaNa, or 30% aq H peroxide (Ref 19a) to give the K salt which is treated with sulfuric acid (Ref 16), syrupy phosphoric acid (Ref 20), or best by passing gaseous HC1 thru a suspension of the K salt in anhyd eth (Ref 19a). It has also been prepd by the action of nitric acid on malonamide,... 

The reaction of condensed phosphoric acid with castor oil gave a poly-phosphoric acid ester, which after neutralization with ammonia shows a high wetting power [32]. Glycerol trioleate was reacted with octametaphosphoric acid at 40°C in the presence of acetic acid anhydride. The reaction product was neutralized with triethanolamine [32,33]. 

Phosphonolipids (glycerophosphonolipids) found mainly in protozoans and marine invertebrates are lipids with phosphoric acid derivatives esterified to the glycerol backbone. 

Phospholipids derived from glycerols, fatty acids, phosphoric acid and a nitrogen containing base (Both have hydrophilic heads and hydrophobic tails)... 

These are the most common class of complex lipid (Figure 12.11) and contain a phosphoric acid residue (phosphate group) and two fatty acids esterified to glycerol. Attached to the phosphate group is an amino alcohol, sometimes referred to as the nitrogenous base, which may be either serine, choline or ethanolamine or sometimes the monomethyl or dimethyl derivatives of ethanolamine (Table 12.4). Alternatively, a polyhydroxy compound which is either glycerol, myo-inositol or one of their derivatives is attached instead... 

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