Endogenous polymer interactions

In the absence of an endogenous centre, the specificity of relaxation data can be improved by introducing in known positions paramagnetic probes. The unpaired electron spin enhances the relaxation rate of the surrounding nuclei in a distance-dependent fashion. In this way, it is possible to evaluate specific interaction sites between a marked polymer and the small molecules. 

Another simple detection method is the polymer-based detection system. This detection system does not depend on the avidin-biotin interaction for localization of the marker enzyme to the antigen but bases on an enzyme conjugated polymer backbone vith attached secondary (link) antibody. This method has the advantage to join both secondary antibody step and the detection complex incubation step in a single step. Consequently, it is a more rapid method and the blocking of the endogenous biotin activity is not necessary. 

As a consequence of penicillin interaction with the membrane of the cell, the pool level of an internal effector undergoes a slow change. The effector can be either an endogenous inducer, whose concentration rises as induction proceeds, or a co-repressor, whose falling concentration derepresses the penicillinase genes. Precursors to various cell-wall polymers are known to accumulate in S. aureus after exposure to penicillin [Park, 95-97 Ito and Saito, 98]. However, none of these compounds is a likely endogenous inducer within the cell, for similar compounds accumulate after treatment with other antibiotics which inhibit cell-wall synthesis (vancomycin, bacitracin) without induction of penicillinase. Penicillin-treated bacilli also do not appear to accumulate these compounds to the same extent as the staphylococci, though penicillinase induction follows. 

The rotational correlation time tr several methods have been proposed to lengthen tr for example, noncova-lent interactions with endogenous macromolecules such as HSA, DNA, specific receptors of the cellular membrane, paramagnetic polymers, liposomes, or micelles. This parameter can be determined by various methods such as NMR of diamagnetic lanthanum complexes or NMR of Gd-complexes. 

The solid-phase extraction (SPE) of steroids involving formation of their inclusion complexes with P-CD polymer has been investigated [27, 28], SPE based on hydrophobic interaction is widely used, however for steroids a new SPE technique based on the formation of inclusion complexes with P-CD has been developed. This technique has been applied for comprehensive sample purification of 45 endogenous or synthetic androgens, 11 endogenous estrogens and 21 corticoids for MS analysis [29],... 

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