An index of the actual or potential activity of a catalyst. The catalytic activity of an enzyme or an enzyme-containing preparation is defined as the property measured by the increase in the rate of conversion of a specified chemical reaction that the enzyme produces in a specified assay system. Catalytic activity is an extensive quantity and is a property of the enzyme, not of the reaction mixture; it is thus conceptually different from rate of conversion although measured by and equidimensional with it. The unit for catalytic activity is the $katal$; it may also be expressed in mol $s^{-1}$. Dimensions: $N T^{-1}$. Former terms such as catalytic ability, catalytic amount, and enzymic activity are no er recommended. Derived quantities are molar catalytic activity, specific catalytic activity, and catalytic activity concentration. Source(s): <a href="http://www.answers.com/topic/catalytic-activity-biochemistry">www.answers.com</a>