Question

What is meant by "sterically possible" and "energetically favorable" for an enzyme-substrate complex to form? (Biochem)

Answer 1

Sterically possible, enzyme-substrate complex to form means, the enzyme and substrate have both structurally inclined to bond with each other or fit into each other, where no steric hindrance is present and they can initiate a conformation change as part of the reaction.

Whereas, 'energetically favorable' means when enzyme-substrate complex is formed, the energy required for reaction to happen is lowered, which means the reaction can go ahead easily and products are formed without any problem, the overall energy of reaction with this meeting of enzyme and substrate gets low, which is favorable for any system, to lower its energy requirement.

Thus an energetically favourable complex will give more product with easily, and the sterically possible complex will form structurally but the reaction may or may not take place if it is energetically unfavourable.