And if enzymes are changed or altered in some way in the reaction at the end of that reaction the enzyme will assume its original shape and original structure. So enzymes are not used up and remain unchanged at the end of the reaction. Now, this is not to say that enzymes during the reaction are unchanged in some way. They might be changed, their structure might be changed. But at the end of the reaction when the enzyme releases the substrate it assumes its original structure and its original shape. So these are the six facts you have to remember about enzymes.