Abstract − Analytical Sciences, 20(2), 273 (2004).
A New Protein Conformation Indicator Based on Biarsenical Fluorescein with an Extended Benzoic Acid Moiety
Jun NAKANISHI,* Mizuo MAEDA,* and Yoshio UMEZAWA**
*Bioengineering Laboratory, RIKEN, Hirosawa, Wako 351-0198, Japan
**Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, and Japan Science and Technology Agency (JST), Tokyo, Japan
**Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, and Japan Science and Technology Agency (JST), Tokyo, Japan
We demonstrate herein a new protein conformation indicator based on biarsenical fluorescein with an extended benzoic acid moiety. The present indicator is reactive to a genetically introduced tetracysteine motif (Cys-Cys-Xaa-Xaa-Cys-Cys, where Xaa is a noncysteine amino acid) of proteins. Compared to the original biarsenical fluorescein (FlAsH) and the biarsenical Nile red analogue (BArNile), the present indicator exhibited larger fluorescence intensity changes in response to Ca2+-induced conformational rearrangements of calmodulin. A calculation of the highest occupied molecular orbital (HOMO) level of the benzoic acid moiety of the indicator molecule supports possible involvement of a photoinduced electron transfer (PET) process. These results indicate that the present indicator is useful for sensitive detection of protein conformational changes.
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