What is the difference between the two calculation modes?

The velocity mode calculates the reaction rate (v) using known Km, Vmax, and substrate values, while the fit mode estimates Km and Vmax from experimental substrate-velocity data pairs using a Lineweaver-Burk linear regression.

How should I format the experimental data pairs in fit mode?

Enter each pair on a new line or separated by spaces in the format 'Substrate,Velocity' (e.g., '0.1,0.2'). You must provide at least two pairs with values greater than zero.

Which types of enzyme inhibition can this calculator model?

It supports competitive (increases apparent Km), uncompetitive (decreases both Km and Vmax), and non-competitive (decreases Vmax only) inhibition models.

What units should I use for the concentrations and velocities?

You can use any consistent concentration units (such as mol/L or M) and velocity units (such as mol/L·s), as long as they match across all input fields.

How does the calculator handle the Lineweaver-Burk fit?

It takes the reciprocal of your substrate and velocity data points, performs a linear regression to find the slope and y-intercept, and derives Km and Vmax from those values.

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Enzyme Kinetics Calculator (Michaelis-Menten)

Calculate reaction velocity with Michaelis-Menten, estimate Km/Vmax via Lineweaver-Burk, and model enzyme inhibition.

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Velocity at [S] = Km

When [S] = Km, the reaction velocity is exactly half of Vmax.

{"result":"v = 0.75 mol/L·s (50% of Vmax) at [S] = 0.5 mol/L. no inhibitor.","metadata":{"result":{"v":0.75,"fractionOfVmax":50}}}

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9 options

ContentPaste or type the main input values.1

Substrate-Velocity Data (S, v) pairstextareaOptionalUsed in 'Find Km & Vmax' mode. At least 2 pairs, both > 0.

SettingsAdjust formats, ranges, numbers, and modes.8

Calculation ModeselectOptionalMax Velocity Vmax (mol/L·s)numberOptionalMaximum reaction velocity at saturating substrate.Michaelis Constant Km (mol/L)numberOptionalSubstrate concentration at half-maximal velocity.Substrate Concentration [S] (mol/L)numberOptionalInhibition TypeselectOptionalInhibitor Concentration [I] (mol/L)numberOptionalInhibition Constant Ki (mol/L)numberOptionalDecimal PlacesnumberOptional

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Enzyme Kinetics Calculator (Michaelis-Menten)

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Examples

1. Calculating Velocity at Substrate Concentration Equal to Km

2. Estimating Km and Vmax from Experimental Assay Data

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