Turnover number

Turnover number has two different meanings:

In enzymology, turnover number (also termed k_cat) is defined as the maximum number of chemical conversions of substrate molecules per second that a single catalytic site will execute for a given enzyme concentration ${\displaystyle [E_{T}]}$. It can be calculated from the maximum reaction rate ${\displaystyle V_{\max }}$ and catalyst site concentration ${\displaystyle [E_{T}]}$ as follows:

For example, carbonic anhydrase has a turnover number of 400,000 to 600,000 s⁻¹, which means that each carbonic anhydrase molecule can produce up to 600,000 molecules of product (bicarbonate ions) per second.

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