Immunological Identity of Soy and Jack Bean Urease

Abstract

Since proteins are usually species specific it might be expected a priori that soy urease would be chemically distinct from jack bean urease. In order to decide this question we have treated clear solutions of soy urease with jack bean antiurease. The antiurease was obtained by injecting crystalline urease into rabbits, followed by purification of the antiurease according to our method. 1 In all cases a precipitin reaction was obtained even when the soy urease contained as little as 1 unit per cc. Furthermore, we have found that soy urease is inactivated by the addition of jack bean antiurease. This inactivation is not so great as the inactivation of jack bean urease by jack bean antiurease. However, the difference is probably due to the presence of colloidal impurities in the soy urease. Table I shows some of our results.

As further confirmation of the inhibitory effect of jack bean antiurease on soy bean urease we have employed animal tests. Soy urease is as toxic to rabbits as is jack bean urease. If soy urease were distinct from jack bean urease one could not expect that injection of jack bean antiurease would confer passive immunity against soy urease. We have made tests, using 4 rabbits. Two rabbits were first given 80 jack bean antiurease units into the ear vein. Then all 4 rabbits were given 50 units of soy urease intraperitoneally. The 2 unprotected rabbits died within 5 hours. The 2 protected rabbits were not affected.