Enzymes are proteins, and therefore their function is specific to their structure. Think of it as a lock and key, if they do not match it will not work. To get more in depth, enzymes are made up of amino acids linked together in a linear chair (primary protein structure). When the protein folds up and takes on different structures, the amino acids will no longer be linear. The order of the amino acids when the protein takes its structure makes it specific to certain substrates.
