Question

The simple Michaelis-Menten model applies only to the initial velocity of an enzyme-catalyzed reaction, that is, to the velocity when no appreciable amount of product has accumulated. What feature of the model is consistent with this constraint? Explain.

Answer 1

Michaelis-Menten model relies on a number of assumptions. During the Veneration and Memorisation of the Derivation, these assumptions may be dashed past by the lecturer doing the mathematical masturbation, and may be ignored by the students trying to grasp the point of the modelling. This is problematic, as not understanding the assumptions leads to the Michaelis-Menten being applied thoughtlessly in situations in which it does not apply.

Which turns out to be almost all situations.

The assumptions are:

The only relevant chemical species in the system are the enzyme (E), the substrate (S), the enzyme-substrate complex (ES‡), and the product (P).
The only relevant chemical reactions occurring in the system are the reversible association of enzyme and substrate to form the enzyme-substrate complex; and the irreversible breakdown of the enzyme-substrate complex to product.
The concentration of the enzyme-substrate complex is constant.

For the Michaelis-Menten model to be applicable to an enzyme in a cell, then these assumptions need to hold.