Substrates bind into enzymes; they are held together at the active site (the "missing" part of the enzyme) with weak bonds. The enzyme can mold its shape to create a stronger bond between it and the substrate.

Lactase is an enzyme used to break down lactose; a disaccharide commonly found in milk. Lactose intolerants have a lactase deficiency, which leads to them breaking down lactose slower.

Enzymes have an ideal Ph and temperature, and when they're removed from an environment with their preferred conditions, they become denaturalized.

All enzyme names end with -ase.