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

In contrast with the coezyme, two. coenzyme analogs, ADP-ribose and SNAD, b ind non-cooperatively to D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) . Palinurus versicolor (PV) GAPDH complexed with ADP-ribose and SNAD has be en crystallized by the method of sitting-drop vapor diffusion. X-ray diffra ction data analysis reveals that both crystals belong to the same space gro up (C2), and have similar cell dimensions: a = 152.80 Angstrom, b = 100.35 Angstrom, c = 128.31 Angstrom, beta = 110.28 degrees and a = 153.41 Angstro m, b = 100.51 Angstrom, c = 128.44 Angstrom, beta = 110.48 degrees, respect ively. 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 p reviously reported for holo- and 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 in duced by the coenzyme binding. The self-rotation function indicates that th e tetramer of these two GAPDH complexes also has good 222 symmetry. The str uctural analysis and the comparison with holo- and apo-GAPDH may give a clu e to the cooperative mechanism of the enzyme.