Purification, crystallization and preliminary X-ray analysis of β-glucosidase from Kluyveromyces marxianus NBRC1777

The intracellular β-glucosidase from Kluyveromyces marxianus NBRC1777 (KmBglI) belongs to glycoside hydrolase family 3 and has a unique domain architecture. Selenomethionine-labelled KmBglI was purified and crystallized by the hanging-drop vapour-diffusion method using the purified enzyme at 30 mg ml⁻¹, 0.04 M potassium dihydrogen phosphate pH 5.1, 16%(w/v) PEG 8000 and 20%(v/v) glycerol. The crystal belonged to space group C2, with unit-cell parameters a = 245.8, b = 148.7, c = 119.9 Å, β = 112.9°. Multiple-wavelength anomalous dispersion data were collected at 2.4 and 2.5 Å resolution. A tetramer was assumed to be present in the asymmetric unit, which gave a Matthews coefficient of 2.6 ų Da⁻¹.