Enzyme Uncompetitive Inhibition Calculator

In uncompetitive inhibition, a drug or molecule binds only to the enzyme-substrate complex — slowing the reaction by reducing both the effective maximum speed and substrate affinity simultaneously. Enter your enzyme's Vmax, Michaelis constant (Km), substrate concentration [S], inhibitor concentration [I], and inhibition constant (Ki) into the Enzyme Uncompetitive Inhibition Calculator to get the Reaction Velocity. Secondary outputs include Inhibition Factor, Percent Inhibition, Apparent Vmax, and Apparent Km.

μmol/min

Maximum enzyme reaction rate under saturating substrate conditions

μM

Substrate concentration at which reaction rate is half of Vmax

μM

Current concentration of substrate in the reaction

μM

Concentration of uncompetitive inhibitor present

μM

Dissociation constant for inhibitor binding to enzyme-substrate complex

Results

Reaction Velocity

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Inhibition Factor

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Percent Inhibition

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Apparent Vmax

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Apparent Km

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Frequently Asked Questions

What is uncompetitive inhibition in enzyme kinetics?

Uncompetitive inhibition occurs when an inhibitor binds only to the enzyme-substrate complex (ES), not to the free enzyme. This type of inhibition decreases both Vmax and Km proportionally, making the enzyme less effective overall.

How does uncompetitive inhibition differ from competitive inhibition?

In competitive inhibition, the inhibitor competes with substrate for the active site. In uncompetitive inhibition, the inhibitor only binds to the enzyme-substrate complex, so it cannot be overcome by increasing substrate concentration.

What is the significance of the inhibition constant (Ki)?

Ki represents the dissociation constant for the inhibitor binding to the enzyme-substrate complex. A lower Ki value indicates stronger inhibitor binding and more potent inhibition.

How do I interpret the apparent Km and Vmax values?

In uncompetitive inhibition, both apparent Km and Vmax decrease by the same factor (1 + [I]/Ki). The apparent Km decreases because the inhibitor removes ES complex from equilibrium, while Vmax decreases due to reduced enzyme availability.

What does the inhibition factor represent?

The inhibition factor (1 + [I]/Ki) shows how much the enzyme activity is reduced. A factor of 2 means the enzyme operates at 50% of its uninhibited rate.

Can uncompetitive inhibition be reversed by increasing substrate concentration?

No, uncompetitive inhibition cannot be overcome by increasing substrate concentration. In fact, higher substrate concentrations may increase inhibition since more ES complex is available for inhibitor binding.

What are typical Ki values for enzyme inhibitors?

Ki values vary widely depending on the enzyme-inhibitor pair, ranging from nanomolar (very potent) to millimolar (weak inhibition). Most drug inhibitors have Ki values in the micromolar range.

How is uncompetitive inhibition used in drug design?

Uncompetitive inhibition is valuable in drug design because it cannot be overcome by substrate competition and becomes more effective at higher substrate concentrations, which often occur in disease states.