Answer
The correct order of events in an enzyme substrate interaction are mentioned below:
1. Substrate entering the active site of enzyme
In this step substrate (molecule which is catalyzed by enzyme) bind to enzyme at its active part. The active site is composed of amino acids which help in attachment of substrate and fit them in best possible way.
2. Enzyme substrate complex
Once enzyme substrate complex is formed, activation energy for reaction start to decrease.
3. Enzyme product complex
In this phase products which are formed from substrate still attach to active site and bond breakage start between product and active site.
4. Product leaving active site of enzyme
Now products are completely detached from active site, while enzyme is get ready to catch another substrate and start another catalytic reaction.