Hey.. I was wondering.. I have just done a lab investigating kinetics of yeast invertase... I mixed invertase, 0.1M phosphate bufer and 0.2M sucrose (substrate) in a test tube and put it in a water bath. at 1,5,10,15 etc minutes I removed some of the invertase and added distilled water.. I was wondering.. why and how does the addition of distilled water stop the reaction occurring?

That is actually strange. I would not think that pure water should actually stop the reaction. Adding a lot of water might reduce the buffer strength but if the added water is pure, the pH should not shift too much. I would have thought that the reaction might actually be stopped with some alkaline solution.

 

Edit: one thing that may be happening is that the invertase concentration was very low. If diluted sufficiently enough the reaction will be effectively slowed down.