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Photoaffinity Labeling of Plasma Proteins
School of Pharmacy, Faculty of Health Sciences, Curtin Health Innovation Research Institute, Curtin University, GPO Box U1987, Perth 6845, WA, Australia
Graduate School of Pharmaceutical Sciences, DDS Research Institute, Sojo University, Kumamoto 860-0082, Japan
* Authors to whom correspondence should be addressed.
Received: 20 August 2013; in revised form: 22 October 2013 / Accepted: 4 November 2013 / Published: 8 November 2013
Abstract: Photoaffinity labeling is a powerful technique for identifying a target protein. A high degree of labeling specificity can be achieved with this method in comparison to chemical labeling. Human serum albumin (HSA) and α1-acid glycoprotein (AGP) are two plasma proteins that bind a variety of endogenous and exogenous substances. The ligand binding mechanism of these two proteins is complex. Fatty acids, which are known to be transported in plasma by HSA, cause conformational changes and participate in allosteric ligand binding to HSA. HSA undergoes an N-B transition, a conformational change at alkaline pH, that has been reported to result in increased ligand binding. Attempts have been made to investigate the impact of fatty acids and the N-B transition on ligand binding in HSA using ketoprofen and flunitrazepam as photolabeling agents. Meanwhile, plasma AGP is a mixture of genetic variants of the protein. The photolabeling of AGP with flunitrazepam has been utilized to shed light on the topology of the protein ligand binding site. Furthermore, a review of photoaffinity labeling performed on other major plasma proteins will also be discussed. Using a photoreactive natural ligand as a photolabeling agent to identify target protein in the plasma would reduce non-specific labeling.
Keywords: photoaffinity labeling; plasma proteins; human serum albumin; α1-acid glycoprotein; photoreactivity; protein binding; labeling specificity
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MDPI and ACS Style
Chuang, V.T.G.; Otagiri, M. Photoaffinity Labeling of Plasma Proteins. Molecules 2013, 18, 13831-13859.
Chuang VTG, Otagiri M. Photoaffinity Labeling of Plasma Proteins. Molecules. 2013; 18(11):13831-13859.
Chuang, Victor T.G.; Otagiri, Masaki. 2013. "Photoaffinity Labeling of Plasma Proteins." Molecules 18, no. 11: 13831-13859.