Sterols structures

The surge of interest in marine sterols, stimulated by some several hundred new and unique sterol structures found in marine invertebrates over the last two... 

Marine Sterols. Several hundred unique sterol structures have been elucidated from a variety of marine invertebrates. A single nucleus can be used to describe most terrestrial sterols, but no single template suffices for marine sterols, Similar to cholesterol, marine sterols play a critical role in both the physiology and biochemistry of biological systems. 

Xu, X. and London, E. (2000) The effect of sterol structure on membrane lipid domains reveals how cholesterol can induce lipid domain formation. Biochemistry 39(5) 843-849. 

Vainio S, Jansen M, Koivusalo M, Rog T, Karttunen M, Vattulainen I, Ikonen E. Significance of sterol structural specificity— desmosterol cannot replace cholesterol in lipid rafts. J. Biol. Chem. 2006 281 348-355. 

That the effect of BR is not simply due to the "oxidized" sterol structure is supported by our observation that oxysterols, which are strong inhibitors in mammalian cell cultures, were nearly inactive in our system. Again this points to... 

In order to save space and repetition of structural fomudae sterol structures are designated by a number (nucleus) and a letter (side chain). The keys are given in Figs. 1 and 2. 

Recrystallized products to constant specific activity-3- Accumulated A sterols structures confirmed by MS and PMR SO = squalene oxide. 

Pigur 7> Eff ct of sterol structural features on biological properties of P. oaotorum. 

Bloch, K., Sterol structure and membrane function, Curr. Top. Cell. Regul., 18, 289—299, 1981. 

Sterol Structure and Membrane Function Konrad Bloch... 

FIG. 7.3 A carbon chain and an oxygen can be molded into a four-ring sterol structure. The later steps in cholesterol synthesis require higher oxygen concentrations. 

Smith, P. F. Relation of sterol structure to utilization in pleuro-pneumonia-like organisms. J. Lipid Res. 5, 121 (1964). 

To speculate on the ultimate origin of biological molecules is a preoccupation that is rapidly growing in popularity. As Roger Stanier put it, it has the same intellectual fascination for some biologists that metaphysical speculation possessed for some medieval scholastics . In that spirit a few thoughts on the evolution of the sterol structure will now be presented. 

It should be recognized that since the majority of these sterol compounds are relatively hydrophobic, direct ionization of these compounds by ESI is not sensitive. Moreover, many of the sterol species carry at least one hydroxyl group. Detection of quasimolecular ions of these sterol species as the form after loss of water is very common. To enhance the sensitivity and stabilize the original structure of a sterol species, appropriate derivatization is commonly employed for characterization and elucidation of sterol structures. Readers who are interesting in this area of work may consult the work of Dr Griffiths and colleagues [50-53]. 

The selenium-dehydrogenation products of isorubijervine have not yet been fully examined, but the two structurally significant products, 5-methyl-2-ethylpyridine and a hydrocarbon, C17H14, m.p. 135-6°, yielding a picrate, m.p. 134-5° and a 1 3 5-trinitrobenzene addition compound, m.p. 165-6°, which identify it as 1 2-ci/cZopentenophenanthrene, indicate for worubijervine, as for rubijervine, a normal sterol structure, for the non-nitrogenous portion of the molecule. ... 

I CHOLECALCIFEROL (VITAMIN A. I Chemical structure. The sterol structure is activated by irradiation of 7-dehydrocholesterol. 

All these results taken together indicate that cyclopropylsterols can replace effectively A -sterols as membrane components in higher plants as well as in other organisms such as the GL7 yeast mutant (7), Mycoplasma capricolum (8) or Tetrahymena pyriformis (9). Further investigations are necessary to determine whether other sterol structures like A -sterols or A ,14a-methylsterols are also suitable for playing a similar role. 

Nelson LD, Johnson AE, London E. How interaction of perfringolysin O with membranes is controlled by sterol structure, lipid structure, and physiological low pH insights into the origin of perfringolysin O-Upid raft interaction. / Biol Chem. 2008 283(8) 4632 1642. 

I should like to suggest that multiple roles for sterol may also exist in photosynthetic plants and that modulation of membrane properties may not be the only thing they do. Multiple roles both within membranes as well as extending into the cytosol would help to explain the diversity of sterol structures which we find in plants. 

The ancestors of these A"-sterol plants may have given rise to the Cactaceae and parts of the Chenopodiaceae. Likewise the A -sterol producing families may have arizen from A -sterol ancestors in the Phytolaccaceae. The 248-alkyl-A -sterols in the Caryophyllaceae would support its more basal assignment since 243-ethyl sterols occur in lower photosynthetic organismsl>2. A careful systematic analysis of additional species in this order will provide further insight into the significance of sterol structural and compositional data with respect to chemotaxonomy. 

---