# What is the unit of specificity constant?

## What is the unit of specificity constant?

1.22. The quotient kcat/Km is called the specificity constant and has the dimensions of a first-order reaction rate constant (M−1s−1). The specificity constant defines the minimal value for k1, the rate of substrate binding; that is, k1>kcat/Km.

## What is the unit of k cat?

The units of Turn over number (kcat) are kcat = (moles of product/sec)/ (moles of enzyme) or sec-1.

What is the unit of Km and Vmax?

Vmax is the maximum enzyme velocity in the same units as Y. It is the velocity of the enzyme extrapolated to very high concentrations of substrate, so its value is almost always higher than any velocity measured in your experiment. Km is the Michaelis-Menten constant, in the same units as X.

### What is the KM?

For practical purposes, Km is the concentration of substrate which permits the enzyme to achieve half Vmax. An enzyme with a high Km has a low affinity for its substrate, and requires a greater concentration of substrate to achieve Vmax.”

### What is the Km of catalase?

Kinetic studies on the activity of catalase conducted using a pressure gauge indicates that the enzyme has a Vmax value of 0.0144, and Km value of 0.00275. The catalase appears to be affected by fluctuating pH values, and operates most ideally at pH 9.

What does kcat km measure?

kcat/KM is the second-order rate constant that determines the reaction rate when the enzyme is mostly free at a very low concentration of the substrate. Both parameters provide critical information on how the enzyme lowers the energy barriers along the reaction pathway for catalysis.

## What are units of Vmax and kcat?

Vmax is a rate, and has units of inverse time built into it; its units are molarity/time, e.g. mol/L-s or mol/L-min. [E] is a concentration, i.e. units of mol/L. When you use this unit, and [E] as concentration, umol. ml-1 for example, you cannot get rid of the volume unit in the final unit of Kcat.

## What is the SI unit of enzyme activity?

Enzyme activity The SI unit is the katal, 1 katal = 1 mol s−1, but this is an excessively large unit. A more practical and commonly used value is enzyme unit (U) = 1 μmol min−1.

What units is Vmax measured in?

The Vmax unit is moles/min, moles/sec, µmoles/min, or µmoles/sec. Vmax depends upon the amount or the concentration of the enzyme as well as the structure of the enzyme.

### What are the units for the Michaelis-Menten equation?

Typical units for vmax are mol m−3 s−1; typical units for Km are mol m−3. As defined in Eq. (12.36), vmax is a volumetric rate that is proportional to the amount of active enzyme present. The Michaelis constant Km is equal to the reactant concentration at which rA=vmax/2.

### What the unit of Michaelis-Menten constant Km is?

Is Km a constant?

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.