Dimethyl phosphatidylethanolamine

However, PE was the poorest substrate for this reaction. Monomethyl phosphatidylethanolamine (MMPE) was somewhat better, and the products were dimethyl phosphatidylethanolamine (DMPE) and PC. The best substrate was DMPE, and 94% of the product was water-soluble after deacylation, as expected for s/i-glycerol-3-phosphorylcholine. The pH optimum was reported to be 8. The highest amount and highest specific activity for DMPE incorporation into PC was found in the 100,(X)()-g pellet, but significant activity was also found in the 15,(K)0-g pellet. 

Phosphatidylcholine can be synthesized by the pathway shown in Figure 14.3. Decarboxylation of phosphatidylserine to phosphatidylethanolamine (cephalin) is followed by methylation in which S-adenosylmethionine is the methyl donor to yield successively the relatively rare mono- and dimethyl derivatives, then phosphatidylcholine. 

PE (trivial name cephalin ) also has a net neutral charge (Fig. 1). PE is widespread and usually the second most abundant phospholipid in animal and plant membranes. It is also the main lipid component of microbial membranes. In animal tissues, phosphatidylethanolamine may exist in diacyl, aUcylacyl and alkenylacyl forms. Moreover, animal phosphatidylethanolamine usually contains higher levels of arachidonic and docosahex-aenoic acids in comparison with the other zwitterionic phospholipid, PC. The partly methylated derivatives of PE (phos-phatidyl-A -methyl-ethanolamine, phosphatidyl-Af -dimethyl-... 

The major glycerophospholipid of Gram-negative bacteria is phosphatidylethanolamine. It is also a major component of some Gram-positive species such as Bacillus. In contrast, phosphatidylcholine is seldom a major lipid in bacteria. In a few genera the ethanolamine head-group may be partly methylated (giving the mono- and dimethyl-derivatives). 

The synthesis of ether phosphatidylethanolamines is analogous to that for the formation of the corresponding phosphatidylcholines (Rosenthal, 1975). The iV-methyl-and AW-dimethyl derivatives have been synthesized from their corresponding phosphatidic acids (Aneja et aL, 1970). The formation of AT-acylphosphatidylethanolamines and other analogues is detailed by Slotboom and Bonsen (1970) and that of ethanolamine plasmalogens in Section 7.5.8. 

Water-soluble fusogens. Large decreases of the surface potential were observed when dipalmitoylphosphatidylcholine (dpPC) was spread on subphases containing glycerol, dimethyl sulphoxide, sucrose, sorbitol or poly(ethyleneglycol) of M.W. 1500 6000 3 x 10 or 5 X 10 (Fig, 1). Similar results were obtained for dipalmitoyl-phosphatidylethanolamine (dpPE). 

DOTMA, l,2-dioleyl-3-iV,iV,iV-trimethylaminopropane chloride DC-Chol, 3-j8-[A-(A, A -dimethyl-ethane)carbamoyl]cholesterol DMDHP, ( )-N,N-[bis(2-hydroxyethyl)]-iV-[2,3-bis(tetradecanoyloxy)propyl]ammonium chloride DMRIE, l,2-dimyristyloxypropyl-3-dimethyl-hydroxyethyl ammonium bromide DOTAP, l,2-dioleoyloxy-3-(trimethylamino)propane DHDEAB, A,A-di-n-hexadecyl-iVA -dihydroxyethylammonium bromide HDEAB, N-n-hexadecyl-iVA -dihydroxyethylammonium bromide MOOHAC, A-methyl-A- -octadecyl-iV-oleyl-iV-hydroxyethylammonium chloride DOMHAC, N-methyl-AA-di-n-octadecyl-iV-hydroxyethylammonium chloride DOHEMAB, A,A-di[0-hexadecanoyl]hydroxyethyl-A-hydroxyethyl-A-methylammonium bromide DOSPA, 2,3-dioleoyloxy-A-[2-(sperminecarboxamido)ethyl]-A,A-dimethyl-l-propanaminium trifluoroacetate DDAB, dioctadecyldimethylam-monimn bromide DOPE, l,2-dioleoyl-propyl-3-phosphatidylethanolamine. 

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