Squalene monooxygenase is an enzyme that works by using NADPH and molecular oxygen to oxidize squalene to two,three-oxidosqualene (squalene epoxide). Squalene epoxidase catalyzes the initially oxygenation action in sterol biosynthesis and is imagined to be just one of the rate-restricting enzymes in this pathway. In human beings, squalene epoxidase is encoded by the SQLE gene. Squalene monooxygenase (SqMO) was formerly referred to as squalene epoxidase (SqE) in the literature.