Crystallographic studies of aspartate racemase from Lactobacillus sakei NBRC 15893

Aspartate racemase catalyzes the interconversion between L-aspartate and D-aspartate and belongs to the PLP-independent racemases. The enzyme from the lactic acid bacterium Lactobacillus sakei NBRC 15893, isolated from kimoto, is considered to be involved in D-aspartate synthesis during the brewing process of Japanese sake at low temperatures. The enzyme was crystallized at 293 K by the sitting-drop vapour-diffusion method using 25%(v/v) PEG MME 550, 5%(v/v) 2-propanol. The crystal belonged to space group P3₁21, with unit-cell parameters a = b = 104.68, c = 97.29 Å, and diffracted to 2.6 Å resolution. Structure determination is under way.