Cholesterol, molecular structure

Cardiolipin or diphosphatidyl glycerol is one of the most ancient membrane phospholipids from phylogenic aspects. It is surprising for such a complex molecule as cardiolipin to have evolved as one of the major membrane lipids in prokaryotics, when steroids such as cholesterol and phytosterols did not. In eukaryotic cells, cardiolipin is exclusively localized within the mitochondria where it is particularly emiched in the outer leaflet of the inner membrane. Even though a molecular structure of cardiolipin has been conserved in entire organisms, its biological significance has escaped attention except in the case of anti-cardiolipin auto-antibodies which are clinically associated with the Wasserman reaction. 

Woodward then moved across town in Cambridge to devote a year of postgraduate study at Harvard University. At the end of that year, he accepted an appointment to the Harvard chemistry faculty, a post he held for most of the rest of his life. One of his great interests at Harvard was the synthesis of large, complex molecules, the first of which was quinine in 1944. He followed that work with the elucidation of other molecular structures and the development of synthetic methods for each. Included among these molecules were penicillin (1945), patulin (1948), cholesterol and cortisone (1951), oxytetracycline (1952), strychnine (1954), lysergic acid (1954), reserpine (1956), chlorophyll (1960), colchicine (1963), cephalosporin C (1965), and vitamin (1971). 

Chloroxytrifluoromethane, 26 137-139 reactions, 26 140-143 addition to alkenes, 26 145-146 oxidative addition, 26 141-145 vibrational spectra, 26 139 Chloryl cation, 18 356-359 internal force constants of, 18 359 molecular structure of, 18 358, 359 properties of, 18 357, 358 synthesis of, 18 357, 358 vibrational spectra of, 18 358, 359 Chloryl compounds, reactions of, 5 61 Chloryl fluoride, 18 347-356 chemical properties of, 18 353-356 fluoride complexes of, 5 59 molecular structure of, 18 349-352 physical properties of, 18 352, 353 preparation, 5 55-57 and reactions, 27 176 properties of, 5 48 reactions, 5 58-61, 18 356 synthesis of, 18 347-349 thermal decomposition of, 18 354, 355 vapor pressures, 5 57, 18 353 vibrational spectra of, 18 349-352 Chloryl ion, 9 277 Cholegobin, 46 529 Cholesterol, astatination, 31 7 Cholorofluorphosphine, 13 378-380 h CHjPRj complexes, osmium, 37 274 Chromatium, HiPIP sequence, 38 249 Chromatium vinosum HiPIP, 38 108, 133 Fe4S4 + core, 33 60 Chromato complexes, osmium, 37 287... 

Finland has a huge forestry industry, and it sponsors a great deal of scientific research involving its own by-products. One of these is sitostanol, derived from pine wood pulp. This compound initially aroused interest because its molecular structure is similar to that of cholesterol. In the course of experiments designed to explore the potential use of pine-tree products in animal feed, researchers noted that the blood-cholesterol levels of animals that consumed sitostanol decreased. Human studies conducted shortly afterwards showed that about three grams of sitostanol per day reduced blood cholesterol by ten to fifteen... 

Another striking difference between normal and cultured skin is shown in Fig. 15.6. As discussed above (see Fig. 15.3c, factor 2), cholesterol-rich pockets containing highly ordered lipid chains are occasionally detected in human skin and are characterized by a Raman-active mode of cholesterol near 700 cm-1 and an intense lipid C-C stretch near 1130 cm-1 in Fig. 15.4a and b, respectively. The intensity of the cholesterol mode is normalized to a Phe vibration near 620 cm-1 and imaged in Fig. 15.6b. As is evident there are many such pockets in the cultured skin model, in contrast to human skin where they are only rarely observed (Fig. 15.3c, factor 2), and usually in the viable epidermis rather than in the SC (as in the cultured skin). These measurements illustrate the power of confocal Raman microscopy for combining spatial measurements with molecular structure characterization. 

Figure C.4. Molecular structures of (a) cholesterol nonanoate (ChNon) and (b) cholesteryl chloride (ChQ). Pure cholesterol has the structure of cholesteryl chloride with the -Cl replaced by a -OH group.

Just as all animal tissues and foods contain cholesterol, which is needed for life itself, all plants have phytosterols, plant sterols. The molecular structures of cholesterol and phytosterols are virtually identical (see the illustration). Because they are so similar, the human body cannot tell the difference. 

Sound too good to be true More than twelve hundred research studies, conducted at top medical centers around the world and published in the most prestigious medical journals, document both the safety and efficacy of phytosterols in cholesterol control. They are completely safe not only because they are naturally found in plants but also because they never enter the bloodstream. After blocking the receptor micelles for probably one to two hours, they are rejected, owing to the slight difference in molecular structure, and are eliminated by the body. Even children and pregnant women can take them without fear. 

AndreollTE. On the anatomy of amphotericin B-cholesterol pores in lipid bilayer membranes. Kidney Int 1973 4 337-45. DeKruijiff B, Demel RA. Polyene antibiotic-sterol interactions in membranes of Acholeplesma laidlawii cellsand lecithin liposomes. III. Molecular structure of the polyene antibiotic-cholesterol complexes. Biochem Biophys Acta 1974 339 57-70. HoIzRW.Theeffectsofthe polyene antibiotics nystatin and amphotericin Bon thin lipid membranes. Ann N Y Acad Sell 974 235 469-79. 

Figure 2.9 In situ STM imaging of l,2-dimyristoyl-sr)-glycero-3-phosphocholine (DMPC) lipid membranes. Molecular structures of the membrane constituents (a) DM PC (b) cholesterol, (c) DM PC...

FIGURE 5.22 Molecular structures of cholesterol (left) and cholesterol chloroacetate (right). 

Figure 6. Molecular structures of azone, ceramide-3 and cholesterol.

Bile acid metabolism in conventional animals is the activity of a balanced ecological system composed of the host, the associated intestinal microflora, and the diet. The host contributes the bile acids themselves and serves to maintain the homeostasis of the gastrointestinal tract. The intestinal microflora alters the molecular structure of the bile acids which it comes into contact with and also profoundly alters the physiological and, to a degree, the anatomical features of the host. The diet contributes the nutrition for both the host and the intestinal microflora and can cause marked changes in the flora s activity toward the bile acids in vivo (52). In addition, the amount of dietary sterols may cause the host to change its absorption and/or catabolism of cholesterol to bile acid and thus the rate of bile acid excretion (53). 

Figure 1. Molecular Structures of Cholesterol Oxidation Products of Interest...

---