Does bitter gourd reduce sugar level?

Yes, it does. This is because it contains a compound called Polypeptide-P, which is similar to insulin and helps reduce blood sugar level.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products