The Inhibition Mechanism Of Flavonoids On Arginine Kinase And α-glucosidase Merging With Molecular Docking

Present paper has conducted the research to the inhibitors of arginine kinase andα-glucosidase using enzyme kinetics, fluorescence quenching and molecular docking. Arginine kinase (AK; EC 2.7.3.3) is a key enzyme in the cellular energy metabolism of insects. The exploration of one kind of effective inhibitor to AK, has provided a pathway to develop environment friendly pesticide. Alpha-glucosidase (EC 3.2.1.20) is a key enzyme in the regulation of glucose metabolism of organisms. Screening on potential effective inhibitors of AGH may provide a pathway for effective chemotherapeutic agents for clinic use in the treatment of diabetes and obesity. The main results of the article are as following:1. The inhibition mechanism of rutin on arginine kinaseOn the basis of the research on the inhibition effect of flavonoids such as quercetin and luteolin to AK in our lab, we studied the another flavonoid, rutin, as the inhibitor of AK, using the enzyme kinetics, fluorescence quenching and molecular docking to explore the inhibition mechanism between rutin and AK.The results indicated that rutin showed strong inhibition to AK and IC₅₀ = 12.3μM, the inhibition constant K_i = 8μM; Rutin is noncompetitive inhibitor to AK by inhibition kinetics; The process of fluorescence quenching is static quenching and the number of binding sites n≈1 between rutin and AK; The thermodynamic parameters at 25oC,ΔG = - 31.96 kJ / mol,ΔH = 60.88 kJ / mol,ΔS = 311.54 J / mol·K; We induced that the interaction between rutin and AK was hydrophobic force according to the value of thermodynamic parameters.To explore the inhibition mechanism between rutin and AK further, we mimic the docking of rutin into AK using molecular docking. The docking results using the software AutoDock4.0 indicated that 3,4-dihydroxyphenyl (B ring) of rutin interacted with the active sites by hydrophobic interaction and the Gly64 interacted with rutin by hydrogen bond. This may be the principal mechanism of inhibition.2. The inhibition mechanism of quercetin onα-glucosidaseThe exploration of the inhibition of flavonoids toα-glucosidase has been attempted, but there is no illustration on the inhibition mechanism. So we choose the flavonoid, quercetin, as theα-glucosidase inhibitor to study the inhibition mechanism.We studied the inhibition between quercetin andα-glucosidase using enzyme kinetics and fluorescence quenching. The results indicated the concentration of quercetin leading to 50%α-glucosidase activity lost IC₅₀=0.78 mM, inhibition constant K_i=0.412 mM; Quercetin is a mixed type inhibitor; The type of fluorescence quenching was the combination between dynamic and static quenching; The number of binding sites n≈1 and the thermodynamics parametersΔG = - 23.79 kJ / mol,ΔS = 91.57 J / mol·K andΔH = 2.398 kJ / molat 13oC; According to thermodynamics parameter, the type of interaction force can be deduced to be hydrophobic interaction.We executed the docking experiment using molecular docking to explore the inhibition mechanism in the structural level. The flexible docking software AutoDock was used to calculate their binding mode and the results indicated 3,4-dihydroxyphenyl (B ring) of quercetin interacted with the active sites by hydrophobic interaction and hydrogen bonds. This may be the principal mechanism of inhibition.The paper choose the two kinds of flavonoids, rutin and quercetin, as the inhibitor of AK andα-glucosidase to explore the inhibition mechanism. The results found that the 3,4-dihydroxyphenyl (B ring) of rutin and quercetin all played an important role in the inhibition to the two different enzymes and this maybe the principal mechanism of the inhibition role of flavonoids in common. This finding also supply us a reference to design effective inhibitor of AK andα-glucosidase.