1. Enzymes have immense catalytic power.
2. The enzymes accelerate (activate) the rate of chemical reaction and do not normally participate in these reactions, if they do so, at the end of the reaction they are recovered as such without undergoing any quantitative or qualitative change.
3. The catalytic power of an enzyme is measured by the turnover number.

Turnover number is defined as the number of substrate molecules converted into product per unit time when the enzyme is fully saturated with substrate. It depends upon its molecular weight.

Example: Transfer of Carbon dioxide from tissues into blood and then to the alveolar air would be less complete in the absence of an enzyme. Carbonic anhydrase is one of the fastest enzymes known.

Each enzyme can hydrate 10 ⁵ molecules of CO ₂ /sec.

For most enzymes, the turnover numbers fall between 1–10 ⁴ per second as shown in Table 6.1.

Table 6.1 Turnover Numbers for Enzymes