#### Km equation

## What is Km value?

km value or Michaelis constant is defined as the substrate concentration at which half of the enzyme molecules are forming (ES) complex or concentration of the substrate when the velocity of the enzyme reaction is half the maximum value.

## What is Km and Vmax?

Vmax is the maximum rate of an enzyme catalysed reaction i.e. when the enzyme is saturated by the substrate. Km is measure of how easily the enzyme can be saturated by the substrate. Km and Vmax are constant for a given temperature and pH and are used to characterise enzymes.

## How do you solve for Vmax and Km?

[S] / v = Km / Vmax + [S] / Vmaxy intercept = Km / Vmax.gradient = 1 / Vmax.x intercept = -Km.

## What is the unit of Km Michaelis constant?

KM is a the concentration substrate required to approach the maximum reaction velocity – if [S]>>Km then Vo will be close to Vmax. KM is a concentration. It will have units of: (M),or ( M),etc. liter liter KM depends only on the structure of the enzyme and is independent of enzyme concentration.

## What is a low Km value?

Km is a constant for any given enzyme and provides a measure of an enzyme’s “affinity” for its substrate. An enzyme with a high Km has a low affinity for its substrate. An enzyme with a low Km has a high affinity for its substrate.

## What does a higher Km value mean?

We define Km as the substrate concentration that gives Vmax/2. The higher the Km of an enzyme, the LOWER its affinity for its substrate. This is because a high Km means that it takes a LOT of substrate before the enzyme gets to Vmax/2.

## What is Vmax equation?

Vmax is equal to the product of the catalyst rate constant (kcat) and the concentration of the enzyme. The Michaelis-Menten equation can then be rewritten as V= Kcat [Enzyme] [S] / (Km + [S]). Km is the concentration of substrates when the reaction reaches half of Vmax.

## How is Vmax calculated?

Ease of Calculating the Vmax in Lineweaver-Burk Plot Next, you will obtain the rate of enzyme activity as 1/Vo = Km/Vmax (1/[S]) + 1/Vmax, where Vo is the initial rate, Km is the dissociation constant between the substrate and the enzyme, Vmax is the maximum rate, and S is the concentration of the substrate.

## What is Vmax value?

The maximal velocity of the reaction (or maximal rate) Vmax is the rate attained when the enzyme sites are saturated with substrate, i.e. when the substrate concentration is much higher than the KM. Examples: Q8W1X2, Q9V2Z6. The Vmax value depends on environmental conditions, such as pH, temperature and ionic strength.

## Can km be negative?

If you follow the disappearance of something, the velocity should be “negative” and hence you need to invert it to get a positive reaction velocity. Only when the reaction rate is positive will you find both Michaelis-Menten parameters to be positive. Also, make sure your reaction rate is faster as [S] increases.

## Is km a SI unit?

The kilometre (SI symbol: km; /ˈkɪləmiːtər/ or /kɪˈlɒmɪtər/), spelt kilometer in American English, is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for 1000).

## Is km an equilibrium constant?

The Michaelis-Menten paradox: Km is not an equilibrium constant but a steady-state constant | bioRxiv.