Enzymes are the machines which make cellular jobs easier. Sometimes they slice and dice, sometimes they connect the dots. In this lab, we used lactase to investigate some enzymatic principles.

In nature, where is lactase found?

Lactase hydrolyses (cuts by adding water) the sugar lactose (note spelling) into two simple sugars, glucose and galactose. Both the initial and final solutions are colourless...therefore, if we did this reaction in lab, we would have no idea of (a) how long the reaction took or (b) even if the reaction proceeded at all.
By substituting nitrophenylgalactoside (NP Gal), we can generate a coloured product, and therefore measure the rate of the reaction.

Ideal Data

	Experiment Two. How does the hydrolysis of lactose change when more enzyme is added?
	Experiment Three. Does the amount of substrate affect the reaction rate?
	Experiment Four. Why do the data peak where they do? Why are the reaction rates essentially zero at both extremes of temperature?

 

 

R.F. Lauff Department of Biology St. Francis Xavier University Antigonish, NS Canada B2G 2W5