Factors that Affect the Activity of Urease Aim: To investigate closely the factors that can affect the activity of urease. The effect of concentration and temperature can be studied over a period of time leading to the order and activation enthalpy of the reaction. Introduction: UREASE (NH 2 ) 2 CO + 3H 2 O ----------> 2NH 3 (aq) + CO 2 (g) Urease is an enzyme found in microorganisms, invertebrates, and higher plants. It catalyses the hydrolysis of urea to ammonia and carbon dioxide. In some bacteria and invertebrates this reaction is the final step in the breakdown of complex nitrogenous compounds before ammonia is excreted. Method: Quench with known volume and concentration of HCl to stop the reaction. Some of the acid will react with the ammonia produced by Urease to determine the amount of HCl used up. Contents of the flask are titrated with standard Sodium Carbonate solution using methyl orange indicator. From the results of this titration, the amount of HCl that did not react with the ammonia can be found by substituting the amount of HCl used to neutralise ammonia can be found. Background Knowledge: An enzyme, such as Urease, is a protein that acts as a catalyst, speeding up the rate at which a biochemical reaction proceeds but not altering the direction or nature of the reaction. An enzyme catalyses virtually every metabolic reaction that takes place within a living organism. Enzyme molecules have a special feature in that they possess an active site. The active site is a region to which another molecule or molecules can bind. This molecule is the substrate of the... ... middle of paper ... ... 23.00 25.20 23.15 5 25.15 26.40 25.45 38ºC Time Amount titrated Amount titrated Average Titration 0 22.90 22.85 22.88 1 29.45 29.55 29.50 2 33.65 33.70 33.68 3 37.10 37.05 37.08 4 39.80 39.80 39.80 5 41.75 41.80 41.78 50ºC Time Amount titrated Amount titrated Average Titration 0 0.35 0.10 0.23 1 0.80 0.60 0.70 2 1.20 1.15 1.18 3 1.55 1.40 1.48 4 1.90 1.60 1.75 5 2.15 1.85 2.00 Activation enthalpy Log of rate on y-axis 1/temp-x-axis – temperature in kelvin (273+temp.)