title: Crystallographic symmetry and coenzyme binding properties of D-glyceraldehyde-3-phosphate dehydrogenase from the tail muscle of Palinurus vulgaris.
abstract: Crystals of apo- and holo-D-glyceraldehyde-3-phosphate dehydrogenase from the tail muscle of the Mediterranean lobster Palinurus vulgaris, previously found to be suitable for single crystal microspectrophotometric studies of catalytic activity in the crystalline state, have been examined by x-ray crystallography. The two forms are isomorphous, space group C 2 with cell dimensions a=128.4 A, b=99.9 A, c=80.3 A,beta=113.4 degrees. These data are consistent with a molecular weight of 73,000 in the crystallographic asymmetric unit, indicating that the tetrameric molecule possesses an exact 2-fold axis both in the presence and in the absence of NAD+. Analysis of the intensity distribution of conventional x-ray precession photographs shows that two further noncrystallographic diads are present and that the molecule has the 2 pseudo 22 symmetry found in other D-glyceraldehyde-3-phosphate dehydrogenases. Binding of NAD+ to apoenzyme in solution, at 25 degrees C, is anticooperative and it can be satisfactorily described by assuming two classes of coenzyme binding sites.
mesh_terms: D000818:Animals; D001051:Apoenzymes; D001665:Binding Sites; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D009132:Muscles / Q000201:enzymology*; D009243:NAD; D008121:Nephropidae; D011485:Protein Binding; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D014961:X-Ray Diffraction
chemical_list: D001051:Apoenzymes; D009243:NAD; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases