Abstract

The NADP-dependent β-keto acyl-carrier protein reductase (BKR) from Brassica napus has been crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol of average molecular weight 1500 as the precipitant. The crystals belong to the hexagonal space group P6422, with unit-cell parameters a = b = 129.9, c = 93.1 à , α = β = 90, γ = 120°. Calculated values for V(m), the use of rotation and translation functions and consideration of the packing suggest that the asymmetric unit contains a monomer. The crystals diffract to beyond 2.8 à resolution 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 of the enzyme and into the evolution of the fatty-acid elongation cycle by comparisons with the other oxidoreductase of the pathway, enoyl acyl-carrier protein reductase (ENR).