Supramolecular complexation of homocysteine and cysteine with cucurbit[7]uril |
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Authors: | Min Jung Lee Nirmal K Shee Jung-In Son Subramanian Karthikeyan Kwang-Hwan Jhee |
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Institution: | 1. Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi, Republic of Korea;2. Department of Chemistry, Kalaslingam University, Tamil Nadu, India |
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Abstract: | Supramolecular complexation of two bio-thiols, homocysteine (Hcys) and cysteine (Cys), by cucurbit7]uril (CB7]) has been fully investigated by 1H NMR spectroscopy, mass spectrometry, isothermal titration calorimetry, and the results were further verified with computational investigations. NMR titration experimental results obviously indicate that the binding stoichiometry of CB7] to Hcys is 1:1 and to Cys is 1:2 in aqueous solution. The binding constants and thermodynamic parameters associated with the complexation between CB7] and the bio-thiols were determined by isothermal titration calorimetry. The energy-minimized structures of the supramolecular complexes of CB7] with Hcys and Cys were determined and provide good agreement with the experimental results. The CB7] cavity is sufficient to include the two Cys, but is unable to accommodate two Hcys due to steric hindrance. The differing binding abilities of Hcys and Cys in aqueous solution towards CB7] host may lead to discriminate them. |
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Keywords: | Supramolecular complexation cucurbiturils homocysteine cysteine molecular recognition |
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