Refinement of Crystallization Conditions for the Crystal Growth Experiment of Animal Lectin (Congerin) in Space and the Evaluation of Grown Crystals

Abstract

Two galectins isolated from the skin mucus of conger eel (Conger myriaster) , congerin I and II, are animal β-galactoside-binding lectins. Congerin I and II are homodimers of 15 kDa subunits composed of 135 and 136 amino acid residues, respectively. Congerins are seemed to participate in the self-defense system including innate immunity on the intra- and extra-body surface of conger eel. Crystals of each congerin grew to the suitable sizes for X-ray diffraction study after one month later. The crystal structures of congerin I, congerin I-lactose complex and congerin II-lactose complex have already been determined at 1. 5 Å resolution level. Refinement of the crystallization conditions to obtain congerin crystals surely within 2 weeks was attempted using a special crystallization apparatus for the STS-107 mission. The solubility, crystal growth rate and diagram of crystallization kinetics were determined for congerin I and II, respectively. Crystals with high quality grow resultingly in 2 weeks by the preliminary trials on earth. Crystals of congerin II diffract X-rays up to 1 Å resolution and are isomorphous to previous ones.