The partial purification and properties of animal and plant hydantoinases.

Hydantoin is rapidly hydrolyzed to hydantoic acid by suspensions of the livers of omnivorous animals (1). Kidney suspensions hydrolyze it more slowly, but other organs are not active. The enzyme responsible for the hydrolysis is absent from all the organs of Herbivora such as the rabbit and guinea pig. It is present, however, in jack bean meal, in beans, peas, and their hulls, and in cucumber and melon seeds. The mammalian and jack bean enzymes show identical specificities in that neither di-substituted hydantoins nor parabanic acid is hydrolyzed (2). They differ, however, in certain properties such as Michaelis constant, pH optimum, effects of temperature, and sensitivity to various drugs. The following is a description of the partial purification of the two enzymes and some quantitative data on their activity.