 The foregoing paragraph is however mistaken as the paragraph equates SDS with CBS which was once thought to be the case but which is now known not to be the case.Comparing human and rat serine dehydratase using a cDNA library was identical except for a 36 amino acid residue stretch.The overall homology between rat SDH and human SDH is 81% in the nucleotide sequence and 84% in the amino acid sequence.