The narrow active-site cleft of O-acetylserine sulfhydrylase from Leishmania donovani allows complex formation with serine acetyltransferases with a range of C-terminal sequences

O-Acetylserine sulfhydrylase (OASS) from L. donovani can bind to serine acetyltransferase (SAT) C-terminus mimicking peptides with a range of bulkiness; the strength of these interactions correlates with the size of the peptide side chains and the size of the active-site cleft. Differences in the interactions of OASS and SAT from various species may be explained by the size of the active-site cleft.