Term structure hypotheses expectations hypothesis

The above categorization attempts to delineate metal-enzyme interactions in terms of structural and functional biochemistry and aims at the establishment of a working hypothesis and a subsequent operational approach. The characteristics of the metal-protein bond serve as the primary parameter for the differentiation of metalloenzymes from metal-enzyme complexes. The spectrum of bond strengths is continuous, of course, and the present discussion focuses attention on its extremes and not on its center, where overlapping behavior must be expected—a situation teleologically related to the behavior of acids and bases. 

As an example, we discuss a structural study, by the Rietveld [10] method, of neutral poly thiophene [11]. This polymer is, sofar, the most ordered polyheterocycle, even though no oriented films have been obtained up to now, and so the only available samples are thermally annealed powders. Interestingly, aside from the expected (and found) co-planarity between adjacent rings, the detected 3-D order can be interpreted in terms of a discrete number of preferred arrangements, each of them shifted with respect to another along the chain axis, and co-present in the crystallites. This hypothesis accounts for the relative doping ease of polythiophene. 

Fluids that follow this hypothesis are termed Newtonian. The hypothesis holds quite well for many nonpolymer fluids, such as gases and water, and solvents, such as toluene. This type of flow behavior would be expected for small, relatively symmetrical molecules, where the structure and/or orientation do not change with the intensity of shearing (particularly those fluids that do not get entangled in one another, as polymers do). 

Corresponding equations were derived for the cysteine proteases ficin, actinidin, bromelain B and D, and the serine proteases subtilisin, chymotrypsin, and trypsin. In all cases, the coefficient of the electronic a term is around 0.4-0.7. Whereas the other regression coefficients in equations (16) and (17) are also relatively similar, the constant terms of both equations differ by about 1.8 log units, which indicates that the lower lipophilicity of the mesyl group, as compared with a much more lipophilic benzoyl group, is responsible for the lower binding affinities of the mesyl amides. To prove this hypothesis, a series of (4-X-Phe)-CONHCH2COO-pyrid-3-yl analogs 12 was synthesized and tested. As expected, lipophilicity determines the structure-activity relationship in this part of the molecules (equation IS). " " ... 

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