Kinetic and thermodynamic insights into the inhibitory mechanism of TMG-chitotriomycin on Vibrio campbellii GH20 exo- β-N-acetylglucosaminidase.

Kinetic and thermodynamic insights into the inhibitory mechanism of TMG-chitotriomycin on Vibrio campbellii GH20 exo-β-N-acetylglucosaminidase.
Carbohydr Res. 2020 Nov 20;:108201
Authors: Morimoto Y, Takahashi S, Isoda Y, Nokami T, Fukamizo T, Suginta W, Ohnuma T
Abstract
We investigated the inhibition kinetics of VhGlcNAcase, a GH20 exo-β-N-acetylglucosaminidase (GlcNAcase) from the marine bacterium Vibrio campbellii (formerly V. harveyi) ATCC BAA-1116, using TMG-chitotriomycin, a natural enzyme inhibitor specific for GH20 GlcNAcases from chitin-processing organisms, with p-nitrophenyl N-acetyl-β-d-glucosaminide (pNP-GlcNAc) as the substrate. TMG-chitotriomycin inhibited VhGlcNAcase with an IC50 of 3.0 ± 0.7 μM. Using Dixon plots, the inhibition kinetics indicated that TMG-chitotriomycin is a competitive inhibitor, with an inhibition constant Ki of 2.2 ± 0.3 μM. Isothermal titration calorimetry experiments provided the thermodynamic parameters for the binding of TMG-chitotriomycin to VhGlcNAcase and revealed that binding was driven by both favorable enthalpy and entropy changes (ΔH° = -2.5 ± 0.1 kcal/mol and -TΔS° = -5.8 ± 0.3 kcal/mol), resulting in a free energy change, ΔG°, of -8.2 ± 0.2 kcal/mol. Dissection of the entropic term showed that a favorable solvation entropy change (-TΔSsolv° = -16 ± 2 kcal/mol) is the main contributor to the entropic term.
PMID: 33243428 [PubMed - as...

Source: Carbohydrate Research - November 20, 2020 Category: Genetics & Stem Cells Authors: Morimoto Y, Takahashi S, Isoda Y, Nokami T, Fukamizo T, Suginta W, Ohnuma T Tags: Carbohydr Res Source Type: research