1H Nuclear Magnetic Resonance Parameters and Spectrogram

Method: 1H NMR spectra was used to detect the conformation of the hydrolyzates. The mixture of samples was 500 μl, the experimental group contained 30 μg enzyme, water-soluble substrate with the final concentration of 18 mM, and 1 mM Ca2+, Ba2+, or Sr2+. Assays were run at 40℃ for 10min and 40min. The standard was 5 mg D-(+)-glucose; and the control group included water-soluble substrate without addition of enzyme. Then 100μl D2O was added to each group before NMR spectra. Finally, all the samples were sent to the Institute for Advanced Research in Central South University for testing hydrolyzates by using Bruker 600 MHz spectrometer (AVANCE III 600M, Switzerland). Results: This is the result of 1H NMR spectroscopy. 1H NMR analysis showed QsGH97a has inverting mechanism to produce β-glucose. The peaks of H-1 α and H-1 β were shown in the group of D-(+)-Glucose, “Ca2+ 10min” represents that the reaction mixture is measured at Ca2+ environment for 10min, “Ca2+ 40min” exhibits that the reaction mixture is detected at Ca2+ environment for 40min. Ba2+-treated groups and Sr2+-treated groups are identical to Ca2+-treated groups.