S(+)-2-Amino-3-(methylamino)propionic acid hydrochloride is a chiral, non-proteinogenic amino acid derivative. Structurally, it is the hydrochloride salt of the S-enantiomer of 2-amino-3-(methylamino)propanoic acid, featuring both a primary and a secondary amine group on a propionic acid backbone. This compound is primarily recognized as a potent agonist at the N-methyl-D-aspartate (NMDA) receptor, specifically targeting the glycine binding site. Due to this activity, it is extensively utilized in neuroscience research to study glutamatergic signaling, synaptic plasticity, and excitotoxicity. It serves as a critical tool compound for investigating neurological disorders such as stroke, epilepsy, and neurodegenerative diseases like Alzheimer's and Parkinson's. As a specialized amino acid analog, it is also employed in peptide synthesis and medicinal chemistry for the development of novel therapeutic agents targeting the central nervous system. Its high purity and defined stereochemistry make it essential for precise biochemical assays and structure-activity relationship (SAR) studies.