Environmental factors such as temperature and pH levels effect enzyme activity. If the temperature is too cold then not enough collisions (not enough kinetic energy) will occur between the substrate and the enzyme so the reaction it catalyses will be slow. If the temperature is too hot the enzyme will be denatured which means the hydrogen bonds on the active site will break changing the shape of it and no longer allowing substrates to bind. The same with pH levels, it can change the charge of the enzyme which prevents the substrate from binding. Some enzymes need additional components to show full activity, these are known as cofactors an example of a cofactor is metal ions. There are two types of enzyme inhibitors one which binds directly to the active site, preventing the substrate from binding and another which binds to another part of the enzyme but still changes its shape not allowing the substrate to bind.