Crystallization of the NADP-dependent beta-keto acyl-carrier protein reductase from Brassica napus

The NADP-dependent beta-keto acyl-carrier protein reductase (BKR) from Bras sica napus has been crystallized by the hanging-drop vapour-diffusion metho d using polyethylene glycol of average molecular weight 1500 as the precipi tant. The crystals belong to the hexagonal space group P6(4)22, with unit-c ell parameters a = b = 129.9, c = 93.1 Angstrom, alpha = beta = 90, gamma = 120 degrees. Calculated values for V-m the use of rotation and translation functions and consideration of the packing suggest that the asymmetric uni t contains a monomer. The crystals diffract to beyond 2.8 Angstrom resoluti on and are more amenable to X-ray diffraction analysis than those reported previously for the Escherichia coli enzyme. The structure determination of B. napus BKR will provide important insights into the catalytic mechanism o f the enzyme and into the evolution of the fatty-acid elongation cycle by c omparisons with the other oxidoreductase of the pathway, enoyl acyl-carrier protein reductase (ENR).