Fluorescence studies on the mechanism for photochirogenesis in the dimerization of 2-anthracenecarboxylate mediated by serum albumins

ORGN 44

Cornelia Bohne, bohne@uvic.ca1, Yoshihisa Inoue, inoue@chem.eng.osaka-u.ac.jp2, Tamara C. S. Pace, tpace@uvic.ca1, Takehiko Wada, hiko@tagen.tohoku.ac.jp3, Masaki Nishijima, nishiji@chem.eng.osaka-u.ac.jp2, Tadashi Mori, tmori@chem.eng.osaka-u.ac.jp2, and Asao Nakamura, asao@sic.shibaura-it.ac.jp4. (1) Department of Chemistry, University of Victoria, PO Box 3065, Victoria, BC V8W 3V6, Canada, (2) Department of Applied Chemistry, Osaka University, Suita, Japan, (3) Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan, (4) Shibaura Institute of Technology, Saitama, Japan
The photodimerization of 2-anthracenecarboxylate (AC) leads to four stereoisomers of which two are chiral. Binding of AC to bovine (BSA) and human (HSA) serum albumins occurs to multiple binding sites. An enatiomeric excess (ee) is observed which is different for each protein. Time-resolved and steady-state fluorescence experiments for AC were employed to gain mechanistic insights for the photochirogenesis. The absence of static quenching demonstrates that dimers are formed in a dynamic process for the bimolecular encounter of excited AC with a ground state molecule. Quenching experiments, employed to selectively quench free and weakly bound ACs, showed that in the case of BSA the largest ee was observed for AC bound to a binding site with moderate binding efficiency. The highest ee of 90% at 5 C was observed for HSA. These results show that balancing the binding efficiency and dynamics is important to control bimolecular reactions within serum albumins.
 

Novel Fluorophores
1:00 PM-5:30 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. R05, Oral

Division of Organic Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008