Analytical Sciences

Abstract − Analytical Sciences, 22(12), 1571 (2006).

Classification of the Binding Modes in Bovine Serum Albumin Using Terminally Substituted Alkane Analogues
Kô TAKEHARA,* Yuki MORINAGA,* Shinya NAKASHIMA,* Shiro MATSUOKA,** Hiroshi KAMAYA,*** and Issaku UEDA***
*Department of Chemistry, Faculty of Sciences, Kyushu University, Ropponmatsu, Chuo, Fukuoka 810-8560, Japan
**Department of Environmental Science, Faculty of Science, Niigata University, Ikarashi, Niigata 950-2181, Japan
***DVA Medical Center and School of Medicine, University of Utah, Salt Lake City, UT 84148, USA
With the fluorescence probe of 8-anilino-1-naphthalenesulfonate (ANS), the binding modes of terminally substituted alkane analogues (CnX; X = COOH, OH, CHO, NH3, CONH2) to bovine serum albumin (BSA) were investigated using a competitive binding technique. The Scatchard plot of the fluorometric titration of BSA with ANS showed that the maximum binding number of ANS, nmax, was 3.81, with the binding constant, Kbnd, of 1.42 × 106 mol-1 dm3. The binding modes of CnX to BSA were analyzed based on the fluorometric titration of the ANS and BSA mixture with CnX. CnCOOH completely displaced the ANS bound to BSA, whereas CnOH and CnCHO displaced only about 40% of the ANS bound to BSA. In contrast, CnNH2 and CnCONH2 displaced very little bound ANS. By comparing these results, we classified the binding modes of CnX to BSA into three types. Two of them are detectable with the ANS fluorescence and the remaining one is not detectable with the fluorescence.