CHAPTER
6
The Metabolism of Phospholipids
R. M. C. DAWSON
Biochemistry Department, Agricultural Research Council, Institute of Animal
Physiology, Bahraham, Cambridge,
England
I. The Biochemistry of Phospholipid Synthesis
267
A. Biosynthesis of Cytidine Diphosphate-"Base" Intermediate .
.
.
267
B. Lecithin and Phosphatidylethanolamine Biosynthesis ....
269
C. Formation of D-1,2-Diglyceride and Phosphatidic Acid
.
.
.
269
D. Sphingomyelin Biosynthesis
270
E. Plasmalogen Biosynthesis
270
F. Biosynthesis of Phosphatidylinositol and Polyglycerol Phospholipids .
271
G. Distribution of Enzyme Systems Responsible for Phospholipid Biosynthesis
271
II. Enzyme Systems That Degrade Phospholipids
272
A. Phospholipase A
274
B. Phospholipase B
277
C. Glycerylphosphorylcholine Diesterase
278
D. Phospholipase C
279
E. Phospholipase D: Properties and Distribution
280
F. Other Enzyme Systems That Degrade Phospholipids .
.
.
.
281
III. The Pathways of Phospholipid Metabolism in vivo
281
References
282
In Chapter 5 it has been well documented that the phospholipids
are ubiquitous in living things. This indicates that the enzymes responsible for their synthesis must also be widely distributed. All plants,
for example, can be successfully grown in culture media devoid of
phospholipids, which shows that they must possess adequate metabolic
systems for synthesizing these compounds. This is also true with the
higher animals such as the mammals, which can be successfully reared
on phospholipid-free diets, and it shows that they can form all the new
phospholipid material required for growth and development. This synthetic capacity must exist even before birth, as the transfer of intact
plasma phospholipids through the placenta is minimal (J).
When the adult mammal is injected with labeled phosphate, acetate,
choline, or ethanolamine there is a comparatively rapid incorporation
265
6
The Metabolism of Phospholipids
R. M. C. DAWSON
Biochemistry Department, Agricultural Research Council, Institute of Animal
Physiology, Bahraham, Cambridge,
England
I. The Biochemistry of Phospholipid Synthesis
267
A. Biosynthesis of Cytidine Diphosphate-"Base" Intermediate .
.
.
267
B. Lecithin and Phosphatidylethanolamine Biosynthesis ....
269
C. Formation of D-1,2-Diglyceride and Phosphatidic Acid
.
.
.
269
D. Sphingomyelin Biosynthesis
270
E. Plasmalogen Biosynthesis
270
F. Biosynthesis of Phosphatidylinositol and Polyglycerol Phospholipids .
271
G. Distribution of Enzyme Systems Responsible for Phospholipid Biosynthesis
271
II. Enzyme Systems That Degrade Phospholipids
272
A. Phospholipase A
274
B. Phospholipase B
277
C. Glycerylphosphorylcholine Diesterase
278
D. Phospholipase C
279
E. Phospholipase D: Properties and Distribution
280
F. Other Enzyme Systems That Degrade Phospholipids .
.
.
.
281
III. The Pathways of Phospholipid Metabolism in vivo
281
References
282
In Chapter 5 it has been well documented that the phospholipids
are ubiquitous in living things. This indicates that the enzymes responsible for their synthesis must also be widely distributed. All plants,
for example, can be successfully grown in culture media devoid of
phospholipids, which shows that they must possess adequate metabolic
systems for synthesizing these compounds. This is also true with the
higher animals such as the mammals, which can be successfully reared
on phospholipid-free diets, and it shows that they can form all the new
phospholipid material required for growth and development. This synthetic capacity must exist even before birth, as the transfer of intact
plasma phospholipids through the placenta is minimal (J).
When the adult mammal is injected with labeled phosphate, acetate,
choline, or ethanolamine there is a comparatively rapid incorporation
265