The function of SDS (serine dehydratase, Ensembl gene identifier ENSG00000135094) is as follows. Catalyzes the pyridoxal-phosphate-dependent dehydrative deamination of L-threonine and L-serine to ammonia and alpha- ketobutyrate and pyruvate, respectively. {ECO:0000269|PubMed:15618015, ECO:0000269|PubMed:15689518, ECO:0000269|PubMed:16580895, ECO:0000269|PubMed:18342636}.