Preliminary crystallographic studies of human mitochondrial NAD(P)(+)-dependent malic enzyme

Human mitochondrial NAD(P)(+)-dependent malic enzyme was overexpressed in E scherichia coli and purified by anion-exchange, ATP affinity, and gel filtr ation chromatography. The protein was crystallized with the hanging-drop va por diffusion method. Many different crystal forms were observed, five of w hich were characterized in some detail. A 2.5-Angstrom multiple-wavelength anomalous diffraction data set and a 2.1-Angstrom native data set were coll ected using synchrotron radiation on crystals containing seleno-methionyl r esidues. These crystals belong to space group B2, with a = 204.4 Angstrom, b = 107.0 Angstrom, c = 59.2 Angstrom and gamma = 101.9 degrees. Self-rotat ion functions demonstrated that the tetramer of this enzyme obeys 222 symme try. (C) 1999 Academic Press.