Purification and Immunochemical Characterization of NADP-Dependent Glyceraldehyde 3-Phosphate Dehydrogenase ofEuglena gracilis1

摘要

NADP-dependent glyceraldehyde 3-phosphate dehydrogenase fromEuglena gracilis(EC 1.2.1.13) was purified about 170-fold by a two-step procedure involving DEAE-SH cellulose chromatography and affinity chromatography on ADP-Sepharose. The homogeneous enzyme from mildly sonicated cells contained equal amounts of two types of subunits with mol wts of 34,000 (A) and 38,000 (B). The active enzyme had a mol wt 144,000 and is therefore an A2B2tetramer. Enzyme from strongly sonicatedEuglenacells contained, in addition, a second allomer with a probable A4structure. NADdependent glyceraldehyde 3-phosphate dehydrogenase, a tetramer with 36,000 mol wt subunits, was unrelated immunologically to the NADP-dependent enzyme although the latter also showed minor NAD-dependent activity. Both isoenzymes of the NADPlinked glyceraldehyde 3-phosphate dehydrogenase, however, were immunologically identical.