Biosynthesis of sphingolipids. The abbreviations used are CMP, cytidine 5′‐monophosphate; CoA, coenzyme A; DG, diacylglycerol; Gal, galactose; Glc, glucose; NeuAc, N‐acetylneuraminic acid; PC, phosphatidylcholine; SM, sphingomyelin and UDP, uridine 5′‐diphosphate.
Vance DE and Vance JE (eds) (2008) Phospholipid biosynthesis in eukaryotes. Biochemistry of Lipids, Lipoproteins and Membranes, pp. 213–244. Amsterdam: Elsevier Science.
Biosynthesis of Lipids | Cholesterol | Biosynthesis
Synthesis of phospholipids and sphingolipids
Glycerol is the starting material in the synthesis of glycerophospholipids. CDP-diacylglycerol is the activated intermediate of this pathway. Sphingolipids are synthesized from palmitoyl CoA and serine, initially to form ceramide. Sphingomyelins and glycolipids are synthesized from ceramide. Various sphingolipids storage diseases are resulted due to hereditary absence of hydrolytic enzymes.
Cholesterol synthesis steps and regulation - SlideShare
Presentation Summary : Most of the fatty acids arise in the cytosol, either through biosynthesis or through triacylglycerol transported from fats depot outside the cell.
Cholesterol Metabolism - PowerPoint PPT Presentation
80% of endogenous cholesterol is formed in the liver. Enzymes involved in the synthesis are partly located in the endoplasmic reticulum and partly in the cytoplasm. Acetyl CoA is the precursor. HMG CoA, mevalonate, isopentenyl pyrophosphate, squalene are some of the important intermediate compounds formed during cholesterol synthesis. Cholesterol is transported in lipoprotein complexes. Elevation of lipids in blood leads to the deposition of cholesterol on the arterial walls leading to atherosclerosis.
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Lipids are digested and absorbed with the help of bile salts. Products of lipid digestion aggregate to form mixed micelles and are absorbed into the small intestine. Lipids are transported in the form of lipoproteins. Fatty acids are activated, transported across mitochondrial membrane with the help of carnitine transporter. β -oxidation of saturated fatty acids takes place in the mitochondrial matrix. Similarly oxidation of unsaturated and odd chain fatty acids also take place with additional reactions. Ketone bodies are formed in the liver but they are utilized by extra hepatic tissues. In uncontrolled diabetes mellitus and starvation, excessive ketone bodies are formed, leading to ketosis. Fatty acid biosynthesis takes place in the cytosol of cells. Fat gets deposited in the adipose tissue. Acetyl Coenzyme A is the precursor of fatty acid synthesis as well as cholesterol biosynthesis. Elevation of lipids in blood leads to deposition of cholesterol plaques in the arterial walls leading to atherosclerosis. Prostaglandins and leukotrienes are synthesized from twenty carbon unsaturated fatty acids. Phosphatidic acid is an important intermediate in the synthesis of glycerophospholipids. In sphingolipids, sphingosine is present as an alcohol.
50 results from de novo synthesis ;
Vance DE and Vance JE (2009) Physiological consequences of disruption of mammalian phospholipid biosynthetic genes. Journal of Lipid Research 50(suppl.): S132–S137.