On the inhibition of alkaline phosphatase by alloxan

Abstract

The inhibition of intestinal alkaline phosphatase by alloxan in vitro has been investigated. The great lack of stability of alloxan in alkaline medium does not permit us to speak its influence at pH 9’4, as in such conditions alloxan undergoes rapid transformation.

The clear inhibition of phosphatase activity can be due to an action proper of alloxan and its transformation products, together with the effect of decreasing pH which alloxan produces by its acidity, the capacity of the usual buffers being unsufficient.

At concentrations 0’01 M and higher, the acidification alloxan produces explains in itself the strong inhibition found. Between 0’01 M and 0’0005 M. concentrations the inhibitions by change of pH cannot account for the whole inhibition produced. At lesser concentrations there are no variations of pH and there are still clear inhibitions by alloxan.

If the change of pH is prevented by bringing the alloxan up to pH 9’4 with NaOH just before the tests, inhibitions continue to be found, but markedly lesser than those obtained with untreated alloxan Solutions.