1991 Volume 67 Issue 10 Pages 209-212
Proteinase A from Aspergillus niger var. macrosporus is a non-pepsintype acid proteinase, whose catalytic site and enzymatic mechanism remain to be clarified. As the first step toward elucidating its three-dimensional structure by X-ray crystallography, proteinase A was crystallized in ammonium sulfate solutions by the hanging-drop vapor diffusion method. In the absence of an organic solvent, only the aggregates of long, thin needles were formed. On the other hand, thicker rodlike single crystals were grown at around pH 1.75 when dimethylsulfoxide (DMSO) was added to a concentration of around 5%. The single crystals of proteinase A thus obtained were suitable for X-ray diffraction measurements with a precession camera.
