Conversely, cold-adapted LDH performs less well when the heat is on. Like all proteins, enzymes are made of chains of smaller molecules, amino acids. Although amino acids form chains by linking together in a similar way, there are around twenty different amino acids that occur commonly in proteins. The properties of a protein are dictated not only by the identity of the amino acids that make it up, but the order in which they occur. These features, in turn, govern how the protein chain folds up into a particular, precise shape.
Enzymes are proteins folded up like knobbly potatoes with a distinctive pattern of folds and clefts.
Sometimes, a pair of chemicals that would react together only slowly will do so millions of times faster, when they find themselves together in a cleft or 'active site' amid the folded protein chain of an enzyme. But enzymes are not multi-purpose molecules. Each one has a very specific talent. LDH, for example, converts a substance called pyruvate to another, lactate, during the production of energy in a process called anaerobic glycolysis. On the other hand, the activity of enzymes depends on their structure.