Dependence affine

Does the alkyl group effect on proton affinity depend on the position of substitution Is the proton affinity oftrans-2-butene (leading to 2-butyl cation) larger, smaller or about the same as that of its isomer, 2-methylpropene Rationalize what you observe. 

Affinity-dependent versus Efficacy-dependent Agonist Potency... 

It has been demonstrated that it is not only the lipophilicity and bulkyness of the ring structures (DPB, thiophene rings, etc.) that may influence the affinity for the transporter. It is clear that the nature of the spacer or linker between these groups and the nitrogen atom in the GABA-mimetic part of the inhibitor play an important role (42,47). Thus, the affinity depends on the presence of a double bond (butenyl vs butyl),... 

Scott, J. E. (1989). Ion binding patterns of affinity depending on types of acid groups. In Mucus and Related Topics, eds. Chantler, E. and Ratcliffe, N. A., The Company of Biologists, Cambridge, pp. 111-115. 

Inhaled nicotine is efficiently delivered to the brain (see chapter by Benowitz, this volume) where it selectively interacts with its central targets, the neuronal nicotinic acetylcholine receptors (nAChRs). The multiple subtypes of uAChR (see chapter by Collins et al, this volume) all bind nicotine but with different affinities, depending on the subunit composition of the uAChR. Binding may result in activation or desensitisation of uAChRs, reflecting the temporal characteristics of nicotine dehvery and local concentration of nicotine. Another level of complexity of the actions of nicotine reflects the widespread and non-uniform distribution of uAChR subtypes within the brain, such that nicotine can influence many centrally regulated functions in addition to the reward systems. In this chapter, we address the consequences of nicotine interactions with nAChRs at the molecular, cellular and anatomical levels. We critically evaluate experimental approaches, with respect to their relevance to human smoking, and contrast the acute and chronic effects of nicotine. 

The affinity of a substrate with its biological target is first connected to its complementarity with this macromolecule target. The molecular recognition and affinity depend on all the favorable interactions that exist in the supramolecular assembly formed between the substrate and the macromolecule. If the presence of fluorine atoms enhances the strength or the number of these favorable interactions, the affinity of the fluorinated substrate will be higher than that of the parent compound. The main parameters involved are the steric and conformational effects, the dipolar/hydrophobic interactions, and the hydrogen bonds. 

Affinity-Dependent Reactions of Reactive Catechols at a Model Biological Receptor... 

Gu, Y., Lee, H., and Hudson, R.A., Bis-catechol-substituted redox-reactive analogs of hexam-ethonium and decamethonium stimulated affinity-dependent reactivity through iron peroxide catalysis, /. Med. Chem., 37, 4417, 1994. 

Functionality. Surface affinity to different solutes is the most important characteristic of solid adsorbents. These affinities depend on the chemical functionality and the surface orientation of the polymer. Affinity can be estimated in the static mode by measuring adsorption isotherms for different organic solutes. 

As with DNA and RNA (3), substrate affinity depends upon the Ca-+ concentration. The lowest /vmapp for nitroplienyl-pdTp-nitrophenyl occurs at mM Ca2+, but for nitrophenyl-pdTp it is 2.5 inM Ca-+. Apart from its effect on K, , Ca2+ increases the Kcnl directly (Fig. 4) maximal effects are observed with about 0.1 M Ca2+. Again in analogy with studies using DNA and RNA (S), all the synthetic substrates show an apparent inhibition of activity when the concentration of Ca2+ is raised above 0.05 M. This effect is solely the result of an increase in Km (Fig. 5). 

H2. Han, S., Zheng, B., Dao Porto, J., and Kelsoe, G., In situ studies of the primary immune response to (4-hydroxy-3-nitrophenyl) acetyl IV-affinity-dependent, antigen driven B cell apoptosis in germinal centers as a mechanism for maintaining self-tolerance. J. Exp. Med. 182, 1635-1644 (1995). 

These two equations show that the affinity depends not only on the internal energy U or the enthalpy Hbut also on the entropy S. 

Both chemical potential and affinity depend on the choice of a standard state. A convenient choice is Ai = 1. The action relative to the standard state (e) is given by ... 

Langmuir s conception of the structure of the atom also threw a flood of light upon the meaning of isotopes—atoms of the same chemical and physical properties but differing in mass. Since chemical affinity depends upon the electrons in the outermost shell, Langmuir believed chlorine isotopes, for example, to have the same number of electrons outside the nucleus. Each chlorine isotope has seventeen free electrons of which seven are in the outermost shell. Since, however, they... 

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