At low temperatures, the rate of reaction will be slow because the enzyme and substrate have low amounts of kinetic energy. This means that there won’t be many collisions so there will be reduced formation of ES complexes. As the temperature is increased, the number of collisions increases, increasing the formation of ES complexes and increasing the rate of reaction. If the temperature becomes really high, hydrogen bonds will begin to break within the protein, causing it to unravel and become denatured. If enzymes are denatured, they lose the shape of their active sites which means they cannot bind to their substrate, decreasing the rate of reaction.