(6-s-fransor (6-s-c/sor extended conformation) steroid-like conformation)
FIGURE 9-7 Conformational flexibility of vitamin D molecules using la,25(OH)2-vitamin D3 [la,25(OH)2D3] as an example. (A) The dynamic single bond rotation of the cholesterol-like side chain of la,25(OH)2D3 (i.e., 360° rotations about five single carbon bonds and the oxygen, as indicated by the curved arrows). The dots indicate the position in three-dimensional space of the 25-hydroxyl group for some 394 readily identifiable side chain conformations which have been determined from energy minimization calculations. Two orientations of the C/D/side chain are presented: a "top" view and an "in-plane" view. (B) The rapid (thousands of times per second) chair-chair interconversion of the A-ring of the secosteroid which effectively equilibrates the la-hydroxyl between the axial and equatorial orientations. (C) The 360° rotational freedom about the 6,7 carbon-carbon bond of the seco /3-ring which generates conformations ranging from the more steroid-like (6-s-cis) conformation, to the open and extended (6-s-frans) conformation of la,25(OH)2D3.
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Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.