Crystallization and improvement of crystal quality for x-ray diffraction of maltooligosyl trehalose synthase by reductive methylation of lysine residues.

Maltooligosyl trehalose synthase, one of the two enzymes in the coupled trehalose biosynthesis system in Sulfolobus acidocaldarius, has been purified and crystallized. The chemical modification of this enzyme by reductive methylation of lysine residues significantly improved the crystal quality for X-ray diffraction experiments. The crystals of the modified enzyme belong to orthorhombic space group P212121, with unit-cell parameters a = 56.70, b = 140.1, c = 205.2 A measured at cryo-temperature, and are found to contain two enzyme molecules per asymmetric unit.