Crystallization and preliminary X-ray crystallographic analysis of extracellular giant hemoglobin from pogonophoran Oligobrachia mashikoi

An extracellular giant hemoglobin of Oligobrachia mashikoi, composed of 24 globins with the molecular mass of ∼400 kDa was crystallized in its intact form. Two crystal forms were obtained by the vapor-diffusion method. Form I crystals obtained using sodium acetate as a precipitant belong to the space group P6122 or P6522, with unit-cell parameters a = 112.41, c = 621.25 Å, and diffracted X-rays beyond 3.0 Å resolution. Form II crystals obtained using PEG 10000 as a precipitant belong to the space group R32, with unit-cell parameters a = 111.50, c = 276.84 Å, and diffracted X-rays beyond 2.9 Å resolution. The crystals are suitable for X-ray crystallography to determine the supramacromolecular assembly of this giant hemoglobin.