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 s^-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].

k_cat = V_max/[E]

References

1. 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.

V_max

Theory overview