Catalyzes the pyridoxal-phosphate-dependent dehydrative deamination of L-threonine and L-serine to ammonia and alpha- ketobutyrate and pyruvate, respectively (PubMed:16580895, PubMed:18342636). Also exhibits racemase activity towards L-glutamate and D-glutamate (By similarity). {ECO:0000250|UniProtKB:A0A6N3IN21, ECO:0000269|PubMed:16580895, ECO:0000269|PubMed:18342636}. This is the function of ENSG00000139410 (SDSL, serine dehydratase like).