Inhibitor Concentration For Competitive Inhibition Of Enzyme Catalysis Calculator

Formula Used:

\[ I = \left( \left( \frac{ \left( \frac{k_2 \times [E_0] \times S}{V_0} \right) - S }{K_M} \right) - 1 \right) \times K_i \]

Final Rate Constant (k₂):

s⁻¹

Initial Enzyme Concentration ([E₀]):

mol/m³

Substrate Concentration (S):

mol/m³

Initial Reaction Rate (V₀):

mol/m³·s

Michaelis Constant (K_M):

mol/m³

Enzyme Inhibitor Dissociation Constant (K_i):

mol/m³

Inhibitor Concentration (I):

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1. What is Competitive Enzyme Inhibition?

Competitive inhibition occurs when an inhibitor molecule competes with the substrate for binding to the active site of an enzyme. The inhibitor resembles the substrate and binds reversibly to the enzyme, preventing the substrate from binding and thus reducing the reaction rate.

2. How Does the Calculator Work?

The calculator uses the competitive inhibition formula:

\[ I = \left( \left( \frac{ \left( \frac{k_2 \times [E_0] \times S}{V_0} \right) - S }{K_M} \right) - 1 \right) \times K_i \]

Where:

\( I \) — Inhibitor concentration (mol/m³)
\( k_2 \) — Final rate constant (s⁻¹)
\( [E_0] \) — Initial enzyme concentration (mol/m³)
\( S \) — Substrate concentration (mol/m³)
\( V_0 \) — Initial reaction rate (mol/m³·s)
\( K_M \) — Michaelis constant (mol/m³)
\( K_i \) — Enzyme inhibitor dissociation constant (mol/m³)

Explanation: This formula calculates the concentration of inhibitor required for competitive inhibition based on enzyme kinetics parameters.

3. Importance of Inhibitor Concentration Calculation

Details: Determining the appropriate inhibitor concentration is crucial for studying enzyme kinetics, drug development, and understanding metabolic pathways. It helps researchers design effective inhibitors for therapeutic applications.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure all values are positive and within reasonable biological ranges for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between competitive and non-competitive inhibition?
A: In competitive inhibition, the inhibitor binds to the active site, while in non-competitive inhibition, the inhibitor binds to a different site on the enzyme, altering its shape and function.

Q2: How does competitive inhibition affect K_M and V_max?
A: Competitive inhibition increases the apparent K_M (the enzyme has lower affinity for substrate) but does not affect V_max (maximum reaction rate can still be achieved with sufficient substrate).

Q3: What are some examples of competitive inhibitors?
A: Common examples include statin drugs that competitively inhibit HMG-CoA reductase, and methotrexate which competitively inhibits dihydrofolate reductase.

Q4: How is K_i determined experimentally?
A: K_i is typically determined by measuring reaction rates at various substrate and inhibitor concentrations and analyzing the data using Lineweaver-Burk or Dixon plots.

Q5: Can competitive inhibition be overcome?
A: Yes, competitive inhibition can be overcome by increasing the substrate concentration, as the inhibitor and substrate compete for the same binding site.