Fig. 1. A modified purification scheme for tubulin polyglutamylase identifies Crithidia p54. (A) Flow chart of the purification scheme using hydroxyapatite chromatography on a CHT-2 column as the final step. (B) Aliquots (30 µl) of successive fractions (500 µl) eluting between 100 and 200 mM sodium phosphate from the CHT-2 column were subjected to SDS-PAGE and proteins were visualised by silver staining. The first lane shows marker proteins with molecular masses in kDa. A 10 µl aliquot of each fraction was also tested for tubulin glutamylation activity using the standard assay (upper panel). Note that a 54 kDa polypeptide copurifies with the glutamylation activity (arrow).