## Does enzyme affect km?

Km is a constant for a given substrate acting on a given enzyme. However, Vmax is directedly proportional to enzyme concentration as Kcat is a constant for a given enzyme.

## What is the significance of Km for an enzyme?

Michaelis constant is a reflection of the affinity of enzyme for its substrate and is characteristic of a particular enzyme-substrate system. The smaller the value of Km, the more strongly the enzyme binds the substrate.

What is the relation between Km and Vmax?

By definition, the KM is the concentration in substrate that gives a rate that is EXACTLY Vmax / 2 (half the Vmax), hence the other name of Km which is half-saturation constant.

Is km a measure of enzyme affinity?

Km may be considered an approximate measure of affinity of an enzyme for its substrate: the lower the Km, the higher is the affinity.

### What is a normal Km value?

For most enzymes, KM lies between 10^-1 and 10^-7 M. The KM value for an enzyme depends on the particular substrate and on environmental conditions such as pH, temperature, and ionic strength.

### How do you calculate km?

From the graph find the maximum velocity and half it i.e. Vmax/2. Draw a horizontal line from this point till you find the point on the graph that corresponds to it and read off the substrate concentration at that point. This will give the value of Km.

What does KM value indicate?

It indicates the affinity of an enzyme for a given substrate: the lower the KM value, the higher the affinity of the enzyme for the substrate. If the enzyme is multifunctional or if the reaction is reversible, we annotate the Vmax for different reactions or for each direction of one reaction.

How do you calculate KM?

## Can km be negative?

Km can never be a negative number because Km denotes the concentration of an enzyme substrate at 1/2 Vmax of enzyme activity.

## Can RNA act as an enzyme?

The excised IVS RNA can act as an enzyme to catalyze sequence-specific cleavage and ligation reactions on substrate RNA molecules. Other systems in which RNA catalysis has been found include related group I IVSs, group II IVSs, ribonuclease P, and certain plant infectious RNAs.

What is a normal KM value?

What makes an enzyme have a low Km value?

A low Km value of an enzyme reflects the high affinity of enzyme for the substrate, whereas a high Km value of an enzyme reflects the low affinity of enzyme for the substrate, e.g. mitochondrial and cytosolic aldehyde dehydrogenase have low and high Km for its substrate acetaldehyde…

### Is the relationship between km and KMAX to substrate and enzyme?

Therefore the relationship between Km and [S] is an inverse. There is no Kmax, there is Vmax as shown in the above equation. Km (the Michaelis constant), is a constant specific for a particular enzyme. As Km is a constant, it is not affected at all by increasing the substrate concentration.

### What does the K M of an enzyme mean?

An enzyme’s K m describes the substrate concentration at which half the enzyme’s active sites are occupied by substrate. A high K m means a lot of substrate must be present to saturate the enzyme, meaning the enzyme has low affinity for the substrate.

How to calculate kcat / Km ratio in enzyme kinetics?

The specific activity with 5µM substrate is 2µM/min/mg. (in my case this is Vmax when I ignore the inhibition). The specific activity with 10µ substrate is 1,7µM/min/mg. (it is lower here, that means here we have inhibition). The specific activity with 20µM substrate is 1,5µM/min/mg. (again inhibition).