Crystallization and Preliminary X-ray Diffraction Analysis of Cold-Active β-Galactosidase from Arthrobacter sp. C2-2

β-Galactosidase from psychrotrophic bacteria strainArthrobactersp. C2-2 catalyzes cleavage of β-D-galactosyl moieties from β-D-galactosides and is interesting for its activity at low temperatures. Various types of crystals with dimensions of up to 0.8 mm were obtained and X-ray diffraction data up to 1.9 Å were collected. The crystals belong to the monoclinic space groupP21with unit-cell parametersa= 140.1 Å,b= 205.7 Å,c= 140.5 Å and β = 102.3°. The enzyme (molecular weight of a monomer is 111 kDa) forms hexamers in the crystal structure (one hexamer per asymmetric unit). The phase problem was solved by molecular replacement. Structure refinement is in progress.