Enzyme, drug affinities

Drug affinity is best quantified in terms of the equilibrium dissociation constant for these varied forms of the target enzyme. 

Pharmacological drug properties regrouping the drug affinity for transporters and enzymes of metabolism... 

Various modified CyDs have been prepared to improve their binding affinities and selectivities controlled by external factors such as photons, metal ions, or pH. Such CyDs can act as chemosensors, artificial enzymes, drug carriers, or reaction fields. CyDs have been used as scaffolds for highly preorganizing functional units. There are aheady many reviews on modified CyDs [1-6, 8, 9, 123-125], so here we summarize only developments reported in the last seven years. 

Uncompetitive antagonism, form of inhibition (originally defined for enzyme kinetics) in which both the maximal asymptotic value of the response and the equilibrium dissociation constant of the activator (i.e., agonist) are reduced by the antagonist. This differs from noncompetitive antagonism where the affinity of the receptor for the activating drug is not altered. Uncompetitive effects can occur due to allosteric modulation of receptor activity by an allosteric modulator (see Chapter 6.4). 

Usually fairly high concentrations of such a drug are needed for effective control of an infection because the inhibitor (the false substrate) should occupy as many active centers as possible, and also because the natural substrate will probably have a greater affinity for the enzyme. Thus the equilibrium must be influenced and, by using a high concentration of the false substrate, the false substrate-enzyme complex can be made to predominate. The bacteria, deprived of a normal metabolic process, cannot grow and multiply. Now the body s defense mechanisms can take over and destroy them. 

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