Crystallization and initial X-ray diffraction analysis of human pyruvate dehydrogenase

Human pyruvate dehydrogenase (E1) is a component enzyme of the pyruvate deh ydrogenase complex. The enzyme catalyzes the irreversible decarboxylation o f pyruvic acid and the rate-limiting reductive acetylation of the lipoyl mo iety linked to the dihydrolipoamide acetyltransferase component of the pyru vate dehydrogenase complex. E1 is an alpha (2)beta (2) tetramer (similar to 154 kDa). Crystals of this recombinant enzyme have been grown in polyethyl ene glycol 3350 using a vapor-diffusion method at 295 K. The crystals are c haracterized as orthorhombic, space group P2(1)2(1)2(1), with unit-cell par ameters a = 64.2, b = 126.9, c = 190.2 Angstrom. Crystals diffracted to a m inimum d spacing of 2.5 Angstrom. The asymmetric unit contains one alpha (2 )beta (2) tetrameric E1 assembly; self-rotation function analysis showed a pseudo-twofold symmetry relating the two alpha beta dimers.