Cholesterol enzyme being affected by a drug. Molecular model of the shape of the human enzyme Hmg-Coa reductase interacting (complexed) with the anti-cholesterol drug Fluvastatin (not seen). The model shows the helices and arrowed sheets representing the enzyme's shape (secondary structure). The shapes of enzymes can be affected by drugs, preventing their function in the body. One of the functions of Hmg-Coa reductase is as the first enzyme in the metabolic pathway that produces cholesterol in the body. High levels of 'bad' cholesterol can contribute to heart disease, and the Fluvastatin drug helps to prevent this by disrupting the function of this enzyme.