Abstract
<p class="PaperH1">Serum albumin is the main drug transporter of the bloodstream and contains two main binding sites: Sudlow I or acidic drug binding site, and Sudlow II or benzodiazepine binding site. Warfarin, a well-known anticoagulant drug commonly used in the prevention of thrombosis and thromboembolism, binds to Sudlow I site, whereas non-steroidal antiinflammatory drugs (NSAIDs) such as diflunisal bind preferentially to Sudlow II site. Albumin is a fluorophore that modifies its fluorescence (quenching or enhancement effect) when it is bound to a drug. The application of the double logarithm Stern-Volmer equation allows the calculation of the stoichiometry and the binding constant of the process. This procedure does not consider the possible interferences coming from the fluorescence of the drug though. Another strategy to evaluate the binding constants is to consider the whole spectrum, taking into account all the possible species in equilibrium; in this case we have used an extended version of the STAR program, which can deal with 300 spectra, each containing up to 300 data points. The aim of this work is to compare both approaches to evaluate the interaction between warfarin (Sudlow I) and diflunisal (Sudlow II) and HSA: the double logarithm Stern-Volmer equation and the STAR program.</p>
Highlights
Albumin, the most abundant protein in plasma and serum, is a water-soluble macromolecule with high biological significance
When a successive amount of the studied drugs is added to a fixed concentration of human serum albumin (HSA), the albumin fluorescence is quenched; this is the case of the HSA fluorescence band at about 285 nm
Diflunisal does not interfere with HSA, while warfarin (Figure 2) interferes about 9 % in the emission mode, over 10% in synchronous 60 nm mode and does not interfere in synchronous 15 nm mode
Summary
The most abundant protein in plasma and serum, is a water-soluble macromolecule with high biological significance. There are some equations to evaluate the fluorescence quenching/enhancement that allow calculating the binding parameters (binding constant and stoichiometry) [4] These equations present several drawbacks, as they consider the albumin as the unique fluorophore, and assume that only one type of interaction is formed and that the concentration of the free drug is much higher than the bound fraction. There often exist other fluorophores in solution (such as the drug or a drug-albumin complex) that force to work under more selective but less sensitive conditions. Another strategy to evaluate the binding constants is to consider the whole fluorescence spectrum, taking into account all the possible species in equilibrium
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
