Enables several functions, including L-serine ammonia-lyase activity; PDZ domain binding activity; and anion binding activity. Involved in pyruvate biosynthetic process; response to lipopolysaccharide; and serine family amino acid metabolic process. Located in cytoplasm and neuronal cell body. Catalyzes the synthesis of D-serine from L-serine. D-serine is a key coagonist with glutamate at NMDA receptors. Has dehydratase activity towards both L-serine and D-serine.