This software is designed as an efficient laboratory tool for the following:
The rate of velocity of catalysis by enzymes varies with the substrate concentration. The velocity increases with the increase in substrate concentration up to a certain point which approaches a maximum velocity Vmax. The Michaelis Constant is the substrate concentration at which the velocity is at half the maximum velocity. The Michaelis Constant is an indication of the affinity of the enzyme for the substrate. The lower the Km, the higher is the affinity. Michaelis-Menton Equation: Vo=(Vmax * [S])/ (Km + [S]). Just enter the inhibition concentration [I], the initial velocities Vo, and the substrate concentrations [S] for each reaction. Select the type of plot (e.g., Lineweaver-Burk). The results for the Michaelis constants Km, the limiting velocities Vmax, the slopes, and the Y-Intercepts will be displayed or you can display the graph.
INHIBITION CONSTANT
The inhibition constant Ki is the dissociation for the enzyme-inhibitor
combination.
If you already know the Michaelis constants and limiting velocities,
then enter the inhibition concentrations [I], Michaelis constants Km, and
limiting velocities Vmax. Select the type of plot used in the calculation
(e.g., Km). The result for the inhibition constant Ki will be displayed
or you can display the graph.
LINEWEAVER-BURK PLOT
The Lineweaver-Burk plot is one way of visualizing the effect of inhibitors
and determining the Michaelis Constant Km and the Limiting Velocity Vmax
from a set of measurements of velocity at different substrate concentrations.
If 1/Vo is plotted against 1/[S], a straight line is obtained where the
slope is equal to Km/Vmax and the y-intercept is equal to -1/Vmax. This
method is usually used for distinguishing the type of inhibition. This
information is used to select the appropriate type of plot needed to calculate
the inhibition constant Ki. If the Lineweaver-Burk plots of several inhibitor
concentrations intersect on the vertical axis, then you have a competitive
inhibitor and should select the Km type of plot. Competitive inhibitors
have the affect of increasing the Km of the reaction and therefore reduces
the affinity of the enzyme for its substrate. If the Lineweaver-Burk plots
of several inhibitor concentrations intersect on the base line, then you
have a non-competitive inhibitor and should select the 1/Vmax type of plot.
Non-competitive inhibitors do not affect the combination of the substrate
with the enzyme, but it does affect the velocity. If the Lineweaver-Burk
plots of several inhibitor concentrations are parallel, then you have an
uncompetitive inhibitor and should select the 1/Km type of plot. Uncompetitive
inhibitors have the affect of decreasing the Km and the velocity of the
reaction to the same extent. If the Lineweaver-Burk plots of several inhibitor
concentrations intersect above or below the 1/[S] axis, then you have a
mixed inhibitor and should select the 1/Km type of plot. Mixed inhibitors
have the affect of decreasing the velocity of the reaction and either increasing
or decreasing the Km.
EADIE-HOFSTEE PLOT
The Eadie-Hofstee plot is another way of visualizing the effect of
inhibitors and determining the Michaelis Constant Km and the Limiting Velocity
Vmax from a set of measurements of velocity at different substrate concentrations.
If Vo is plotted against Vo/[S], a straight line is obtained where the
slope is equal to -Km and the y-intercept is equal to Vmax.
HANES-WOOLF PLOT
The Hanes-Woolf plot is another way of visualizing the effect of inhibitors
and determining the Michaelis Constant Km and the Limiting Velocity Vmax
from a set of measurements of velocity at different substrate concentrations.
If [S]/Vo is plotted against [S], a straight line is obtained where the
slope is equal to 1/Vmax and the y-intercept is equal to Km/Vmax.
Requires Windows 3.1, 3.11, 95, 98 or NT
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