Cryptophane Xenon-129 Nuclear Magnetic Resonance Biosensors Targeting Human Carbonic Anhydrase

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• 作者：Jennifer M. Chambers ; P. Aru Hill ; Julie A. Aaron ; Zhaohui Han ; David W. Christianson ; Nicholas N. Kuzma ; Ivan J. Dmochowski
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：January 21, 2009
• 年：2009
• 卷：131
• 期：2
• 页码：563-569
• 全文大小：210K
• 年卷期：v.131,no.2(January 21, 2009)
• ISSN：1520-5126

文摘

¹²⁹Xe NMR biosensors are promising agents for early disease detection, especially when their interactions with target biomolecules can perturb ¹²⁹Xe chemical shifts well beyond the typical field inhomogeneity of clinical MRI. We introduce human carbonic anhydrase (CA) as a single-binding-site enzyme for studying xenon biosensor−protein interactions. A xenon-binding cryptophane was substituted with linkers of varying lengths to p-benzenesulfonamide to yield nondiastereomeric biosensors with a single ¹²⁹Xe NMR resonance. X-ray crystallography confirmed binding of the eight-bond-linked biosensor containing a single xenon atom in the CAII active site. Biosensor dissociation constants (K_d = 20−110 nM) were determined by isothermal titration calorimetry (ITC) for isozymes CA I and II. The biosensor−CA complexes yielded “bound” hyperpolarized ¹²⁹Xe NMR resonances of narrow line width that were shifted by 3.0−7.5 ppm downfield, signifying much larger shifts than seen previously. Moreover, isozyme-specific chemical shifts clearly differentiated CA I and II, despite their similar structures. Thus, xenon biosensors may provide a powerful strategy for diagnosing human diseases characterized by the upregulation of specific CA isozymes and other protein biomarkers.