Conformational flexibility information

The sedimentation coefficient s°, or its normalized form 5 0 w function of the conformation and flexibility of a macromolecule (via its translational frictional property) and its mass. So if we are going to obtain conformation and flexibility information we need to know the molecular weight (molar mass)... 

Chemithon film sulfonating-sulfating systems, 23 544-547 Chemithon reactor, 23 544 Chemoinformatics, 6 1-25 chemical databases, 6 19-20 chemical information retrieval, 6 6—19 chemical information storage, 6 2-6 chemical library design, 6 17-18 clustering techniques, 6 16-17 conformational flexibility, 6 10-11 conformational searches, 6 10-11 data analysis and preparation, 6 20-21 data searching, 6 6-19 diversity searches, 6 14-18... 

Of great interest to the molecular biologist is the relationship of protein form to function. Recent years have shown that although structural information is necessary, some appreciation of the molecular flexibility and dynamics is essential. Classically this information has been derived from the crystallographic atomic thermal parameters and more recently from molecular dynamics simulations (see for example McCammon 1984) which yield independent atomic trajectories. A diaracteristic feature of protein crystals, however, is that their diffraction patterns extend to quite limited resolution even employing SR. This lack of resolution is especially apparent in medium to large proteins where diffraction data may extend to only 2 A or worse, thus limiting any analysis of the protein conformational flexibility from refined atomic thermal parameters. It is precisely these crystals where flexibility is likely to be important in the protein function. 

Conformation dictates overall molecular size and shape, and influences molecular properties as well as chemical reactivity. Experimental information about conformation is often scarce, and computational methods may need to stand on their own. There are actually two different problems associated with treatment of conformationally-flexible molecules. The first is to identify the appropriate conformer (or conformers), and the second is to locate it (them). Both of these will be touched on in turn. 

With this information at hand, Maruoka and coworkers developed a new C2-symmetric chiral quaternary ammonium bromide 12 which incorporated an achiral, conformationally flexible biphenyl subunit (Scheme 5.8) [12]. 

The conformationally flexible group serves to both relay and amplify the stereochemical information of the existing stereogenic centre, thus enabling efficient control of diastereos-electivity (Scheme 1.11). 

The GPC-viscometry with universal calibration provides the unique opportunity to measure the intrinsic viscosity as a function of molecular weight (viscosity law, log [17] (it versus log M) across the polymer distribution (curves 3 and 4 in Fig. 1). This dependence is an important source of information about the macromolecule architecture and conformations in a dilute solution. Thus, the Mark-Houwink equation usually describes this law for linear polymers log[i7] = ogK+ a log M (see the entry Mark-Houwink Relationship). The value of the exponent a is affected by the macromolecule conformations Flexible coils have the values between 0.5 and 0.8, the higher values are typical for stiff anisotropic ( rod -like) molecules, and much lower (even negative) values are associated with dense spherical conformations. 

Whereas the extreme conformational flexibility of acyclic dithioacetals limits the amount of structural information available from... 

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