Abstract
Crystals of the tetrameric xylose isomerase from Streptomyces violaceoniger have been examined by x- ray analysis. Octahedral crystals with a maximum di- mension of 0.7 mm were grown from ammonium sul- fate solution. They possess the symmetry of P41212 or P43212 space groups, which are crystallographically indis4inguishable.The unit cell dimensions are a = b = 140 A and c = 134 A. There is one tetramer of molec- ular weight 160,000per asymmetricunit. The crystals diffract to 2.2 A.