Leu-Enkephalin is a naturally occurring pentapeptide opioid that acts as an endogenous ligand at mu and delta opioid receptors, participating in pain modulation, stress response and neuroendocrine signaling in research models. It is supplied as a high-purity white lyophilized powder at >=99% HPLC purity in sealed vials, offering good stability and straightforward reconstitution. It is widely used in opioid-receptor pharmacology, analgesia mechanism studies and neurochemistry research, supporting cell-based assays and preclinical experimental protocols with consistent batch quality. Strict quality control is applied to every production batch, and we can supply batch-specific COA documents upon request. Unopened material should be stored sealed at 2-8 degree C in a dry, dark place; for longer storage -20 degree C is advised while avoiding repeated freezing and thawing. We support trial orders and large-volume supply, with OEM and custom private-label options and discreet worldwide shipping available. For research purposes only, not for human or veterinary use.