ASSOCIATION EQUILIBRIUM OF D-METHAMPHETAMINE AND 1-METHAMPHETAMINE WITH SERUM-ALBUMIN

The association equilibria for complex formation between serum albumin (bovine, rat) and the optical isomers of methamphetamine (MAMP) was d etermined using an ultrafiltration method. It was found that serum alb umin/d-MAMP and serum albumin/l-MAMP complexes had distinctly differen t Scatchard plots with bovine and rat albumin. The binding parameters of each association equilibrium were estimated from the Scatchard plot s by Rosenthal's graphic method. This distinguished two kinds of speci fic binding sites in terms of the association equilibrium between bovi ne serum albumin and d-MAMP, and one binding site for rat serum albumi n and d-MAMP. One specific binding site was found between serum albumi n and l-MAMP in both bovine and rat. Molar ellipticities, [theta], of peaks were decreased in the CD spectra of the complexes formed between bovine serum albumin and d-MAMP or l-MAMP when compared with the CD s pectrum of bovine serum albumin alone. However, no difference in [thet a] was found between the CD spectra of the enantiomers of MAMP in the measured wavelength range. The non-specific binding site was distinct from the specific binding site and resulting from altered tertiary str ucture of the albumin molecule. (C) 1998 Wiley-Liss, Inc.