Food Chemistry and Fish in Nutrition

4.3.5. Synthesis of phospholipid

4.3.5. Synthesis of phospholipids

The phospholipids are synthesized either from phosphatidate, e.g. phosphatidylinositol, or from 1,2-diacyl glycerol, eg, phosphatidylcholine and phosphatidylethanolamine.

1. Formation of phosphatidate

It is formed by the reaction between 1,2 diacylglycerol and ATP in the presence of a kinase.

                                      Kinase                                      

1,2 diacylglycerol + ATP   → 1,2 diacylglycerolphosphate + ADP

 

 

2. Fomation of phosphatidyl choline (lecithin)

Cholie+ ATP → Chloine monophosphate
Chloine monophosphate + CTP → CDP-Chloine + PPi
CDP-Chloine + 1,2 diacylglycerol → Phosphatidyl choline + CMP
3. Fomation of phosphatidyl ethanolamine (Cephalin)

Cephalin is formed from Ethanolamine and CTP

Ethanolamine+ ATP → Ethanolamine monophosphate
Ethanolamine monophosphate + CTP → CDP-Ethanolamine + PPi
CDP-Ethanolamine + 1,2 diacylglycerol → Phosphatidyl Ethanolamine + CMP

4. Formation of Phosphatidyl inosital

In the synthesis of phosphatidyl inosital, cytidine triphosphate (CTP), a high energy phosphate formed from ATP, reacts with phosphatidate to form a cytidine- diphosphate- diacylglycerol (CDP-diacyglycerol). Finally, this compound reacts with inositol, catalyzed by the enzyme CD-diacylglycerol inositol transferase, to form phosphophatidylinositol.

Cytidine triphosphate (CTP) + phosphatidate ↔ CDP-diacylglycerol

CD-diacylglycerol inositol transferase

CDP-diacylglycerol + Inositol → Phosphophatidylinositol

please click to see the image of synthesis of triglycerides and phospholipids