# Kcat

The catalytic constant (k_{cat}) or turnover number is the number of enzymatic reactions a single saturated enzyme molecule can catalyze per unit of time, usually expressed in ^{-1}. k_{cat} is not dependent on the concentration of the enzyme, and is, therefore, a better parameter than V_{max} for comparing different enzymes. Because k_{cat} is the maximum number of chemical reactions a single enzyme molecule can catalyze, the maximum velocity (V_{max}) at a specific enzyme concentration is obtained by multiplying k_{cat} with the concentration of the enzyme ([E]), i.e., V_{max} = k_{cat} • [E]. This means, that if V_{max} and [E], which can be experimentally measured, are known, k_{cat} can be calculated as follows [1].

_{cat} = V_{max}/[E]

## References

- Lehninger, Albert L.; Nelson, David L.; Cox, Michael M. (2008).
*Principles of Biochemistry*(5th ed.). New York, NY: W.H. Freeman and Company. ISBN 978-0-7167-7108-1.