How do enzymes work and what would be the effects of an increasing temperature on an enzyme controlled reaction?

Enzymes are biological catalysts that work by increasing the speed of a reaction, without being altered or used up in the reaction. Each enzyme has an active site specific to a particular substrate and therefore is complementary to its substrate molecule. The substrate molecule fits into the active site and a reaction occurs, the product of the reaction leaves and the enzyme remains unaltered and ready to accept another substrate. Increasing the temperature increases the rate of the reaction. Both enzyme and substrate molecules have more energy and therefore move around more, increasing the chance of a collision. However, if the temperature increases past the optimum temperature the enzymes will start to denature - and will unravel altering the shape of the active site so substrates can no longer fit and a reaction can no longer occur.