Category: Enzymes


  • According to M–M equation, at very high values of [S], the initial velocity Vo asymptotically approaches Vmax. In practice, however, it is very difficult to accurately assess Vmax from direct plots of Voversus[S] (from hyperbola curve). Only when the graph is linear, we can determine the Vmax. Therefore, the M–M equation is algebraically transformed into other forms…

  • M–M equation is sufficient to describe most of the enzyme-catalysed reaction. It can be utilised to determine Km and Vmax at various substrate concentration, and the values can be used in predicting rate-limiting steps

  • Applications

  • Significance

  • The Km value can be determined from Michaelis plot, LB plot, and Eadie Hofstee’s plot.

  • Properties

    It is independent of enzyme concentration but dependent on substrate conc. It varies with pH and temperature. Typically, the Km values lie between 10−2 to 10−5 moles/litre for various enzymes as given in Table 6.4.   Table 6.4 Km Value for Different Enzymes

  • Units

    Km is expresses in moles per litre.

  • Definition It is defined as the concentration of the substrate at which the initial rate is half the maximal rate.

  • The three situation at A, B, and C on hyperbola curve can be verified from the M–M equation.

  • The rate equation for the breakdown of ES may be given by the sum of two reaction – one is the backward reaction of equation 1 and the other is the forward reaction of equation 2. Thus, Assume the rate of formation of ES from E + P is very small (K4), hence can be ignored. When the…