What is the affect of temperature and pH on enzyme activity?

All enzymes have an optimal temperature and pH level in which they perform the best. Usually low temperatures and really high temperatures will slow down or stop an enzyme. The high temperatures will often denature the proteins within the enzymes. As for the pH level, that also depends on the nature of the enzyme. For example, if the enzyme is working in the stomach then its optimal pH will be higher because the stomach is very acidic. However, as it is with temperatures, anything really higher or lower than what the enzymes needs can hamper its productivity.

Temperature affects enzymes in two ways. In lower temperatures, the molecular energy is reduced, thus slowing down the rate of reaction. In higher temperatures, the enzyme's structure can actually be changed, and seeing enzymes are very specific to their reaction, will make the enzyme not function. On graphs, with temperature as the independent variable, You often see a slow rise in reaction rate as temperature increases, then suddenly falls. This explains this.

Don't have any specific things for PH. Sorry.

Most enzymes just erally are at peak performance when the temp. and PH. are somewhere in the middle. With temperature, they don't work best very cold or very hot, just in the middle. As with PH, they work best around 7, which is neutral. Not too acidic, not too basic.