Comments |
The Michaelis constant, KM, and the maximal rate, Vmax, can be readily
derived from rates of catalysis measured at a variety of substrate concentrations
if an enzyme operates according to the simple scheme given in
equation 23 in ref. The derivation of KM and Vmax is most commonly achieved with the use of curve-fitting programs on a computer (see the appendix to
chapter 8 for alternative means of determining KM and Vmax). The KM
values of enzymes range widely (Table link). For most enzymes, KM lies between
10^-1 and 10^-7 M. The KM value for an enzyme depends on the particular
substrate and on environmental conditions such as pH, temperature,
and ionic strength. The Michaelis constant, KM, has two meanings. First,
KM is the concentration of substrate at which half the active sites are filled. Second, KM is related to the rate constants of the individual steps in the
catalytic scheme. |