Eadie-Hofstee Plot Calculator

The Eadie-Hofstee Plot Calculator is used in enzyme kinetics to visualize the relationship between reaction velocity and the velocity-to-substrate ratio — a graphical method for determining key enzyme parameters without requiring data linearization. Enter your Km (Michaelis constant), Vmax (maximum reaction velocity), and a list of substrate concentrations to get the slope (−Km), Y-intercept (Vmax), correlation coefficient (R²), and total data points analyzed.

μM

Substrate concentration at half maximum velocity

μmol/min

Maximum velocity of the enzyme reaction

Enter substrate concentrations separated by commas (μM)

Results

Slope (-Km)

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Y-intercept (Vmax)

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Correlation Coefficient (R²)

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Data Points Analyzed

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Results Table

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Frequently Asked Questions

What is an Eadie-Hofstee plot and how is it used in enzyme kinetics?

The Eadie-Hofstee plot is a linear transformation of the Michaelis-Menten equation that plots velocity (v) against v/[S]. It provides an alternative method to determine Km and Vmax values, with the slope equal to -Km and the y-intercept equal to Vmax.

How do I interpret the slope and y-intercept of an Eadie-Hofstee plot?

The slope of the Eadie-Hofstee plot equals -Km (negative Michaelis constant), while the y-intercept equals Vmax (maximum velocity). A steeper negative slope indicates lower substrate affinity (higher Km).

What are the advantages of Eadie-Hofstee plots over Lineweaver-Burk plots?

Eadie-Hofstee plots provide more even distribution of data points and are less sensitive to errors at low substrate concentrations compared to Lineweaver-Burk plots. They also give equal weighting to all data points.

What is the significance of Km and Vmax in enzyme kinetics?

Km represents the substrate concentration at which the reaction velocity is half of Vmax, indicating enzyme-substrate affinity. Vmax is the maximum reaction velocity when the enzyme is saturated with substrate.

How many data points do I need for a reliable Eadie-Hofstee plot?

A minimum of 5-6 data points spanning a wide range of substrate concentrations is recommended. Include concentrations both below and above the Km value for optimal accuracy.

What does the correlation coefficient (R²) tell me about my data?

The correlation coefficient indicates how well your data fits the linear model. Values closer to 1.0 indicate better linearity and more reliable Km and Vmax determinations.

Can I use the Eadie-Hofstee plot for inhibitor studies?

Yes, Eadie-Hofstee plots are useful for analyzing enzyme inhibition. Different inhibition types produce characteristic changes in slope and intercept patterns compared to the uninhibited enzyme.