Met-enkephalin is a naturally occurring peptide in the body that belongs to the class of compounds known as opioid peptides. It is derived from larger precursor proteins and plays a crucial role in modulating pain, stress, and emotional responses. Met-enkephalin primarily binds to opioid receptors in the brain, which helps to reduce the perception of pain and promote feelings of well-being. This peptide is found in various tissues, including the brain and spinal cord, and is involved in several physiological processes. Research on met-enkephalin has implications for understanding pain management and developing treatments for conditions like chronic pain and depression.