Question

The Vmax of the isoform of glycogen phosphorylase expressed in muscles is significantly larger than the isoform of the enzyme expressed in the liver enzyme. Explain the functional significance of this observation.

Answer 1

Answer and Explanation: In enzyme kinetics, one constant describing enzyme activity is Maximal Velocity (Vmax). It indicates how fast an enzyme can catalyze the reaction. It is dependent on substrate concentration.

As the muscle is an organ which needs a great amount of energy, the enzyme glycogen phosphorilase is very active on the organ, compared to the liver, where glicose is stored. So, the Vmax of glycogen phosphorylase expressed in muscle is faster than when expressed in the liver, means the enzyme in muscle has a bigger concentration of substrate and therefore will reach Vmax faster, i.e. will be significantly larger.