Lecture 4

• Polyprenoids

  ❖ ubiquinone, a member of the respiratory chain in mitochondria

  ❖ dolichol, which takes part in glycoprotein synthesis

  ❖ plant-derived isoprenoid compounds: rubber, camphor, the fat-

  soluble vitamins A, D, E, and K, and β-carotene
• Monoterpenes

  ❖ they are found in the essential oils of many plants

  including fruits, vegetables, and herbs

  ❖ they are involved in the biosynthesis of high terpene resins, and other compounds with different biological functions

  ❖ monoterpenes prevent the carcinogenesis process and are effective in treating early and advanced cancers
• Steroids precursor of bile acids, adrenocortical hormones, sex hormones, vitamin D, cardiac glycosides, sitisterols of plant and some alkaloids. Found particular in nervous tissue, major constitu of plasma membrane and plasma lipoproteins
• Cholesterol synthesis in ER and cystosol
• Regulation of cholesterol synthesis: SREBP, translation of mRNA, degradation of reductive , phosphorylation
• Apolipoproteins are cofactors, part of lipoproteins, inhibitors, ligands, receptors. Synthesized in liver and intestine
• Chylomicrons carry lipids from intestine, mainly consist of triacyglycerols, apolipoprotien forms spherical shell (fat globule) and external face is hydrophili. Release lipoprotein lipases on blood vessels . Liver takes up chylomicrin remnants
• Very Low Density lipoproteins transport triacyglycerols, cholesterol in excess. Use apo- B-100 and E. Are hydrolysis by lipases on capillary surface remenants are IDL
• IDL processed by liver or converted to LDL by removal of triacylglycerol
• LDLcarry cholesterol in blood, linoelate common fatty acyl chain, shell of phospholipid, surrounded by hydrophobic core. Contains apo B-100
• Cells outside liver get cholesterol by LDL apo B-100 binding to LDL the receptors (coated pits) which contain Cathrine invaginate to,plasma membrane and fuse to form a vesicle and fuse with lysosomes to degraded LDL. Protein part becomes AA, cholesterol part used in cell and activate acyl-CoA
• HDL pick up cholesterol from dying cells and release in liver tissue to synthesize cholesterol