Two-dimensional 1H and 1H-detected NMR study of a heterogeneous biocatalyst using fast MAS at high magnetic fields

Varghese, Sabu and Halling, Peter J. and Häussinger, Daniel and Wimperis, Stephen (2018) Two-dimensional 1H and 1H-detected NMR study of a heterogeneous biocatalyst using fast MAS at high magnetic fields. Solid State Nuclear Magnetic Resonance, 92. pp. 7-11. ISSN 0926-2040 (https://doi.org/10.1016/j.ssnmr.2018.03.003)

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Abstract

Nuclear magnetic resonance (NMR) is a powerful tool for investigating atomic-scale structure in heterogeneous or composite materials where long-range order is absent. In this work solid-state 1H and 1H-detected NMR experiments were performed with fast magic angle spinning (νR = 75 kHz) and at high magnetic fields (B0 = 20 T) and used to gain structural insight into a heterogeneous biocatalyst consisting of an enzyme, human carbonic anhydrase II (hCA II), covalently immobilized on epoxy-functionalized silica. Two-dimensional 1H-1H NOESY-type correlation experiments were able to provide information on 1H environments in silica, epoxy-silica and the immobilized enzyme. Two distinct signals originating from water protons were observed: water associated with the surface of the silica and the water associated with the immobilized enzyme. Additional two-dimensional 1H-1H double–single quantum (DQ-SQ) correlation experiments suggested that the immobilized enzyme is not in close contact with the silica surface. Most significantly, comparison of two-dimensional 1H-15N spectra of the immobilized enzyme and the solution-state enzyme confirmed that the structural integrity of the protein is well preserved upon covalent immobilization.

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