The turnover number is defined as the maximum number of substrate molecules that can be converted into product molecules per unit time by an enzyme molecule. the concentration of enzyme active sites is not necessarily equal to the concentration of enzyme molecules, because some enzyme molecules have more than one active site. if the enzyme molecule has one active site, the turnover number is given by turnover number=/[e]t= is often written as ) if the enzyme molecule has more than one active site, then we multiply [e]t by the number of active sites to determine its effective concentration. determine the value of the turnover number of the enzyme carbonic anhydrase, given that rmax for carbonic anhydrase-249 ㎛ol. l-1 s-1 and [e].-2.88 nmol. l-1. carbonic anhydrase has a single active site