This study used high-performance affinity chromatography (HPAC) and immobilized human serum albumin (HSA) columns to examine the specificity and cross-reactivity of various compounds that have been proposed as markers for the minor binding sites of HSA. These agents included acetyldigitoxin and digitoxin as probes for the digitoxin site, phenol red as a probe for the bilirubin site, and cisor trans-clomiphene as markers for the tamoxifen site. None of these probes showed any significant binding at HSA's indole-benzodiazepine site. However, phenol red did bind at the warfarin-azapropazone site of HSA, and cis/trans-clomiphene gave positive allosteric effects caused by the binding of warfarin to HSA. Digitoxin and acetyldigitoxin were found to bind to a common, unique region on HSA; cis- and trans-clomiphene also appeared to interact at a unique site, although trans-clomiphene displayed additional direct competition with phenol red. From these results it was possible to develop a model that described the general relationship between these binding regions on HSA. This information should be useful in future studies that employ HPAC for characterizing the binding of HSA to other drugs or clinical agents.

Bulk and nanosized MAX and MXene phases are comparatively evaluated for microwave absorption and Li-ion battery anode applications.

High-performance affinity chromatography and zonal elution studies were used to examine the binding that takes place between the drug clomiphene and the protein human serum albumin (HSA). Equations were derived to describe the behavior of zonal elution experiments in which a solubilizing agent is present in the mobile phase to aid in the dissolution of a competing agent or injected analyte. These equations were then used to determine the association equilibrium constants for the clomiphene/HSA system, with beta-cyclodextrin being used as a complexation agent to improve the water solubility of cis- and trans-clomiphene without affecting the nature of their binding to HSA. It was found in these studies that both cis- and trans-clomiphene have 1:1 interactions at a common binding region on HSA (association constants at pH 7.4 and 37 degrees C: cis, 7.5 x 10(6) M-1; trans, 1.3 x 10(6) M-1). Further competition experiments between cis- or trans-clomiphene and various site-selective probes indicated that the clomiphene-binding region is the same as the proposed tamoxifen site of HSA. The approach and equations used within this report are general ones that can be applied to zonal elution studies of other solute-ligand systems in which one or more of the test components have limited solubility in the desired mobile phase.

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