Integrated multi-spectroscopic and molecular docking techniques to probe the interaction mechanism between maltase and 1-deoxynojirimycin, an α-glucosidase inhibitor

Abstract

Interaction mechanism of an antidiabetic agent, 1-deoxynojirimycin (DNJ) with its target protein α-glucosidase (maltase), was investigated by kinetics, fluorescence spectroscopy, UV-vis spectroscopy, circular dichroism, dynamic light scattering coupled with molecular docking analysis. It was found that DNJ reversibly inhibited activity of maltase through a mixed-type manner with IC of (1.5±0.1) μM and inhibition constant K of (2.01±0.02) μM. Fluorescence data and UV-vis information confirmed that the intrinsic fluorescence of maltase was quenched by DNJ through a dynamic quenching procedure due to the collision of them. The calculated thermodynamic parameters including enthalpy change, entropy change and Gibbs free energy change indicated that their binding was spontaneous and the driven force was hydrophobic interaction. Besides, circular dichroism analysis displayed that their binding resulted conformational changes of maltase, characterizing by a decrease of α-helix and an increase in β-sheet. Dynamic light scattering measurements demonstrated the reduction in the hydrodynamic radii of maltase. Further molecular docking revealed that DNJ formed hydrogen bonds with catalytic residues Asp68, Arg212, Asp214, Glu276, Asp349 and Arg439 of maltase, then inhibited the enzyme activity by occupying catalytic center. This study provided a comprehensively understanding about the action mechanism of DNJ on maltase.

Altering the inhibitory kinetics and molecular conformation of maltase by Tangzhiqing (TZQ), a natural α-glucosidase inhibitor

“…IC 50 values and kinetic parameters from Line weaver-Burk double-reciprocal-plots and Dixon plots were used as approaches to enzyme inhibition [ 22 ]. The results showed that TZQ exhibited an obvious inhibition against maltase, similar to acarbose, flavonoids in the leaves of Morus atropurpurea and 1-deoxynojirimycin (DNJ) [ 23 , 24 ]. DNJ and flavonoids in mulberry leaves were reported to be alkaloid and flavone components in TZQ, and the results for rats were similar to those observed in this study [ 7 ].…”

“…For anticompetitive inhibition, the lines are parallel. When a mixed inhibition mechanism existed, the data lines intersect in the second or third quadrant on the Line-weaver Burk plots [ 24 – 26 ]. The results showed that the substrate concentration lines intersected at the y-axis, and with the increase in the concentration of TZQ, no change was observed in the V max values, while the K m values increased, indicating that this sample acted as a competitive inhibitor, similar to acarbose [ 27 – 29 ].…”

“…Additionally, the inhibitory constant of the DNJ equivalent for maltase was 2.1 × 10 − 4 mM, and the inhibitory activity was shown to be competitive [ 32 ]. However, Wu et al reported that DNJ reversibly inhibited the activity of maltase in a mixed-type manner with an IC 50 of (1.5 ± 0.1) μM and an inhibition constant Ki of (2.01 ± 0.02) μM [ 24 ]. Competitive inhibition behaviour has been reported for some active fractions and ingredients in previous studies [ 32 ], which is the same result as the TZQ sample used in the current study.…”

ELISA Test on Cordia myxa L. Leaf Extract for alpha-Glucosidase Inhibitor

“…5 The resulting base on the IC 50 value of sample compares with the IC 50 of positive control. 7 The on this case IC 50 value will show the best activity if equal or less than IC 50 value of positive control. 8 On this method the researcher will need relatively more sample to investigate 5 so to reduce the needs of the sample it will use by another method such as ELISA.…”

White Mulberry (Morus alba) as a natural source of antidiabetic compounds ·

“…Ponadto, dokowanie molekularne wykazało, że DNJ może wiązać się w domenie katalitycznej glukozydazy i oddziaływać z resztami aminokwasowymi przez tworzenie wiązań wodorowych i oddziaływań hydrofobowych. Te badania wyjaśniają szczegółowo mechanizm interakcji DNJ z enzymem, co w przyszłości może umożliwić firmom farmaceutycznym projektowanie nowych leków, będących inhibitorami α-glukozydazy opartych na związkach polihydroksylowanych alkaloidów, takich jak DNJ [14,15].…”