Phospholipids, regiospecific

Thompson, D.H., Svendsen, C.B., MegUo, C.D. and Anderson, V.C. (1994) Synthesis of chiral diether and tetraether phospholipids regiospecific ring opening of epoxy alcohol intermediates derived from asymmetric epoxidation. The Journal of Organic Chemistry, 59, 2945-2955. 

Phospholipase A2 Hydrolysis of Phospholipids Use of 31P NMR to Study the Hydrolysis, Acyl Migration, Regiospecific Synthesis, and Solubilization of Phospholipids... 

The new 31p-NMR results also allow us to directly establish the specificity of various phospholipases by direct product observation and should also be very useful in regiospecific chemical synthesis of phospholipids. 

Squalene oxidases enantiospecifically and regiospecifically epoxidize the terminal double bond of squalene 1 to give (31S )-squalene epoxide 258. This, in turn, is the precursor of triterpenes and sterols (e.g., 3) in both plants and animals. Squalene oxidases are found in higher forms of life with the probable exception of insects and terrestrial annelids. They are also present in algae and other lower forms with the possible exception of some bacteria. The enzyme system requires molecular oxygen, NADPH and FAD as well as supernatant protein and phospholipids. There is no evidence for the participation of cytochromes P-450. 

The triethylsilyl ether 147 thus formed regiospecifically from the diol 150 [Rl=(BnO)2 (0), R2=Bn], which was optically resolved by a chiral column chromatography, was transformed to Ins(2,4,5)P3 and Ins(l,4,5)P3 (Schema 3-23). At this stage, temporary protection of OH-1 with the silyl group is not necessary, i.e. 150 can be directly phosphorylated by the phosphite-phosphonium approach as described in the section on phosphorylation (Scheme 2-6). H The diol 150 was used furthermore as a versatile synthetic intermediate for the synthesis of myo-inositol 1,2-cyclic-4,5-trisphosphate 152 (Scheme 3-23), 8 2-acyl analogues of Ins(1,4,5)P3, and inositol phospholipid. 

Immunocytochemical analysis of cucumber cotyledons on the first day of germination revealed a selective binding to the phospholipid monolayer of the lipid bodies [62,63]. Moreover, it was shown that translocation of the lipoxygenase is paralleled by a 4-fold stimulation of the enzymic activity as well as a change in the regiospecificity of its reaction towards AA in favour of the formation of 85-HpETE... 

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