chemical reaction:

Question

E + S <=> E~S <=> E-S
<=> indicates a bidirectional reaction
with different forward and backward rate constants. we can call these k1, k2, k3 and k4 in the above equation.

Here, the enzyme binds to the substrate; the initial complex E~S then undergoes a conformational change to E–S.

How do we write differential equations for the changes of concentrations of E~S and E-S with time? and solve them?