Studies on enzyme action. XIX.—Urease: a selective enzyme. II.—Observations on accelerative and inhibitive agents

Abstract

In the previous communication experiments were described which had been made with the Urease present in the Soja bean proving that the enzyme is strictly selective in its action and that whilst its activity is much reduced by ammonia it is increased, in a remarkable manner, by the presence of carbonic acid: in other words, the two products of change affect the activity of the enzyme in opposite ways—a result altogether without precedent. In explanation of these results, the suggestion was made that Urease is a feebly acidic substance. Though it was obvious that the results were not to be harmonised with the views that were current as to the manner in which enzymes act, we refrained from comment, deeming it desirable to obtain more information before discussing the new situation that was created. In the interval, the behaviour of other enzymes has been under observation by Dr. E. F. Armstrong and ourselves and it is proposed to discuss the general outcome of the work, in a comprehensive communication, at an early date. Meanwhile, we desire to bring forward an account of further observations on Urease carried out with the object of ascertaining the manner in which the activity of the enzyme is affected by the presence of various substances together with the urea.