Drugs usually used to combat HIV. The HIV genome contains a large sequence that is transcribed and translated all at once, then cleaved into smaller, functional proteins by a protease. These drugs block the protease from acting, so this large series of genes remains as one long polyprotein inside the cytoplasm until it is eventually degraded. Virus particles do not form and infect other cells. Most effective when coupled with two nucleoside analogs such as AZT. This enzyme made such a useful target because it is a novel protein, unlike any others found in normal eukaryotic cells. This means very few, if any, side effects.