Crystallographic studies on the binding of coenzyme analogs to D-glyceraldehyde-3-phosphate dehydrogenase fromPalinurus versicolor

In contrast with the coezyme, two coenzyme analogs, ADP-ribose and SNAD, bind non-cooperatively to D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH).Palinurus versicolor (PV) GAPDH complexed with ADP-ribose and SNAD has been crystallized by the method of sitting-drop vapor diffusion. X-ray diffraction data analysis reveals that both crystals belong to the same space group (C2), and have similar cell dimensions: a =152.80 Å,b =100.35 Å, c =128.31 Å,β =110.28° and a =153.41 Å,b =100.51 Å,c =128.44 Å,β =110.48°, respectively. It is estimated that the asymmetric unit in each crystal contains 4 subunits. This is a novel crystal form which is quite different from that previously reported for holoand apo-GAPDH from the same source. The result suggests that the binding of the two coenzyme analogs to GAPDH may lead to some significant conformational changes, which are different from those induced by the coenzyme binding. The self-rotation function indicates that the tetramer of these two GAPDH complexes also has good 222 symmetry. The structural analysis and the comparison with holoand apo-GAPDH may give a clue to the cooperative mechanism of the enzyme.