Crystallization of a new class of microbial ribonuclease from Rhizopus niveus

Crystals of ribonuclease Rh, a new class of microbial ribonuclease from Rhizopus niveus, were obtained from polyethylene glycol 8000 solution by a vapour diffusion technique in the hanging drop mode. Two crystal forms, type I and type II, were obtained from the same droplet solution. Both forms belong to the space group P2(1)2(1)2(1), but their cell dimensions are markedly different: a = 68.3 A, b = 73.0 A, c = 50.0 A for type I and a = 67.5 A, b = 72.3 A, c = 44.2 A for type II. The type I crystals diffract beyond 2.0 A resolution and are suitable for X-ray structure analysis at high resolution.