In order to investigate the inhibition type and inhibition constant
([K.sub.i]) values of extracts, Lineweaver-Burk and Dixon plots were used against a-glucosidase enzyme.
The research was done in steps to obtain structural and electronic properties of Ops, fullerene derivatives proposals and its complexes, as well as docking energies and inhibition constant
(b) Secondary plot for calculation of steadystate inhibition constant
([K.sub.i]) of compound 4b.
These plots reveal if the ligand has the ability to form a slowly dissociating step and what the on- and off-rate constants of the slowly dissociating step are, the dissociation constant of the fast step ([K.sub.A]), and the inhibition constant
of the other ligand.
The strength of such inhibition is described by the inhibition constant
([K.sub.i]) whose value depends on the specific antibiotic and substrate.
However, the inhibition degree will vary with the substrate concentration and at low substrate concentrations the hydrolysable tannin will be a better inhibitor because of the smaller value of its inhibition constant
[K.sub.i1] (see legend of Figure 5).
Parameter Findings Mechanism of inhibition Uncompetitive Inhibition constant
(equal to [IC.sub.50] 1.11 [+ or/] 0.20 mmol/l in this kind of inhibition) Predicted binding energy [DELTA]G -7.84 kcal/mol H-bond: Tyr 341 Predicted interactions [pi]-[pi] interaction: Tyr 72, Trp 286, Tyr 341
The inhibition constant
(Ki value) and mechanism were elucidated for compounds which shown strong inhibitory potential.
Kinetic study of angustidine (2) on BChE suggested a mixed inhibition mode with an inhibition constant
(Ki) of 6.12 [micro]M.
Complex Energy score Number of H-bond Hydrophobic interaction interaction 2W9I/CID: 1990283 -6.01 2 (Ser343, Lys346) 5 Complex Total intermolecular Estimated interaction energy, inhibition constant
, Kcal/Mol ([K.sub.i]) nM 2W9I/CID: 1990283 -8.64 570.38
The values of the constants ([K.sub.i]) thus obtained indicate that these plants can be investigated in pharmacotherapeutic for eventual treatment, including the plant "Salvia officinalis" which presented the lowest values of inhibition constant
for both aqueous and methanolic extracts.
All the natural phospho-donors (acetyl phosphate, carbamoyl phosphate, phosphoramidate, and monophosphoimidazole) bind to active site with binding energy ranging from -3.32 to -3.93 kcal/mol and inhibition constant
from 1.31 mM to 3.67 mM (Table 1).