enzymes are usually composed of which type of molecule
Enzyme Enzymes are known to catalyze more than 5,000 biochemical reaction types.[4] Most enzymes are proteins, although a few are catalytic RNA molecules. The latter are called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures.
Pepsin Pepsin is an endopeptidase that breaks down proteins into smaller peptides (that is, a protease). It is produced in the stomach and is one of the main digestive enzymes in the digestive systems of humans and many other animals, where it helps digest the proteins in food. Pepsin has a three-dimensional structure, of which one or more polypeptide chains twist and fold, bringing together a small number of amino acids to form the active site, or the location on the enzyme where the substrate binds and the reaction takes place. Pepsin is an aspartic protease, using a catalytic aspartate in its active site.[2]