Fluorescence Studies of Chicken Serum Albumin Interactions with Drugs

School of Earth, Mineral and Natural Sciences, Federal University of Technology, P. M. B. 1526, Owerri, Nigeria

Manuscript received 9 February 1988, revised 28 June 1988, accepted 1 September 1988

The binding of either dicoumarol or warfarin to chicken serum albumin (CSA) quenches the native tyrosine fluorescence of the protein. The interaction results in an increase in the intrinsic fluorescence of warfarin and a shift in the wavelength of maximal emission from 400 to 395 nm. An increase in the intrinsic fluorescence of dansylglycine on binding to CSA is accompanied by a blue-shift in the wavelength of maximal emission of the drug, thus indicating the hydrophobic nature of the binding sites for these drugs.

CSA has one strong affinity site for warfarin (K=3.7 x 10⁶ M^-1) as well as an intermediate number of much weaker sites. The protein has three strong affinity sites for dicoumarol with an average K of 6.8 x 10⁶ M^-1 and several number of much weaker (secondary) sites.