α-Conotoxin EIIB (Alpha-conotoxin EIIB) is a toxin peptide that can be obtained from Conus ermineus. α-Conotoxin EIIB binds to nAChR ( K i =2.2 nM). α-Conotoxin EIIB can be used in the study of neurological diseases such as schizophrenia, drug addiction, Alzheimer's disease, and Parkinson's disease.