Final answer:
Nitric oxide is produced in the body by an enzyme called nitric oxide synthase (NOS) which converts L-arginine into nitric oxide and citrulline. NOS plays a crucial role in regulating physiological functions such as blood pressure and neurotransmission.
Step-by-step explanation:
Nitric oxide is produced in the body by several different enzymes. One of the enzymes that produces nitric oxide is the enzyme nitric oxide synthase (NOS). NOS converts the amino acid L-arginine into nitric oxide and citrulline. This process is important for regulating various physiological functions in the body, such as blood pressure and neurotransmission.