Masumi Taki
The University of Electro-Communications (UEC)
Masumi Taki is an associate professor, head of the chemical biology laboratory, in department of engineering science at graduate school of UEC. He got awards at 5th international summer school on supramolecular chemistry (Poland), Chemical Society of Japan, the Society of Synthetic Organic Chemistry (Japan) in 1996, 1997, and 2008, and 2010. His former research career is: 1) JSPS research fellow at Gunma University, Okayama University, and Tokyo University in 1996-2002; 2) research fellow at AIST and at GenoFunction, Inc. in 2002-2003; 3) assistant professor of Okayama University in 2003-2011; 4) Caltech visiting research associate at biology division in 2007-2008.
6-propionyl-2-(dimethylamino)naphthalene (PRODAN) is a well-known solvatochromic fluorescence reporter which shows both turn-on and color-changing effect when exposed in a hydrophobic environment [1]. Because of its extreme small size with lipophilic/nonionic property, we hypothesize that it can be interacted weakly with various hydrophobic pockets of most target biomacromolecules such as proteins. A conjugation of an appropriate surrounding structure to PRODAN core would strengthen both specificity and affinity to the target along with the solvatochromism, and consequently create a target-specific fluorogenic sensor.
Meanwhile, we have established a library construction system, namely gp10 based-thioetherification (10BASEd-T), by conjugation between artificial molecules as the cores and randomized library peptides as the surroundings [2, 3]. By using this system, PRODAN core was conjugated with randomized peptide library on T7 phage, and selection against a target protein (glutathione-S-transferase; GST) was performed. After several rounds of biopanning, a consensus sequence of NTVSC*HGF (C* represents PRODAN-hybridized Cys) was found. The chemically synthesized hybrid showed intense blue-cyan fluorescence only when GST was present. After the addition of excess amounts glutathione (GSH; a natural ligand of GST), it disappeared and weak yellow fluorescence appeared instead. Detailed results such as obtaining dissociation constant, thermodynamic parameters, and epitope-mapping upon the specific interaction between the hybrid sensor and GST will also be presented [4].
[1] Weber, G., Farris, FJ. (1979) Biochemistry, 18, 776–9.
[2] Fukunaga, K., Hatanaka, T., Ito, Y., Taki, M. (2013) Mol. BioSyst., 9, 2988–91.
[3] Fukunaga, K., Hatanaka, T., Ito, Y., Minami, M, Taki, M. (2014) Chem. Commun., 50, 3921–3; inside cover article.
[4] Taki, M., Inoue, H., Mochizuki, K., Yang, J, Ito, Y. (2016) Anal. Chem., 88, 1096–99 (2016).
