L-Cycloserine is the enantiomer of D-cycloserine and is primarily used as a research chemical rather than a clinical antibiotic. Unlike D-cycloserine, which treats multidrug-resistant tuberculosis by inhibiting bacterial cell wall synthesis (specifically enzymes like alanine racemase and D-alanyl-D-alanine ligase involved in peptidoglycan formation), L-cycloserine has limited antibacterial activity. It is investigated for its potent antagonistic effects at the glycine binding site of NMDA receptors in the brain, potentially enhancing cognitive function, fear extinction, and treating neurological and psychiatric disorders such as anxiety, PTSD, schizophrenia, and OCD. Due to its neuroactive properties, it requires careful handling in research settings.