Crystallization and Preliminary X-Ray Diffraction Analysis of Tomato ß-Galactosidase 4

In tomato fruits, at least seven β-galactosidase genes are expressed during fruit development and maturation. Tomato β-galactosidase 4 (TBG4) have unique enzyme properties and substrate specificities which has both β-galactosidase / exo-β-(1→4)-galactanase activities. It is important to examine the structure of TBG4 to clarify this unique substrate recognition mechanism. An extracellular TBG4 was crystallized from 0.1 M tris(hydroxymethyl) aminomethane (Tris) buffer using polyethylene glycol (PEG) as a precipant. The crystals belonged to space group P2₁2₁2 or P2₁2₁2₁, with cell dimensions a=92.34, b=95.73, c=158.93 Å. The crystals diffracted to 2.2Å resolution using synchrotron radiation. Calculation of the Matthews coefficient suggested the presence of two monomers per asymmetric unit (V_M= 2.16Å/Da).