Enzyme Specificity Using Beta-Galactosidase and Alpha-Galactosidase Lab

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Enzyme Specificity Using Beta-galactosidase and Alpha-galactosidase

Introduction: In order to survive, organisms need reactions to occur at a certain time and place. Enzymes make these reactions happen. Enzymes are highly specific causing only one enzyme to catalyze one reaction. “Induced fit” explains why enzymes act this certain way. An enzyme will surround a certain substrate and form to it for the reaction to occur in the active site. If it doesn’t form to it, the reaction will not occur. The first enzyme being used, beta-galactosidase, is an active ingredient in Lactaid. Lactaid helps break down lactose. The second enzyme being used, alpha-galactosidase, is an active ingredient in Beano which catalyzes the breaking down of melibiose. Melibiose and lactose are both disaccharides composed of two simple sugars galactose and glucose. So, can Lactaid break down melibiose as well as lactose (the substrate it is specific to) or Beano break down lactose as well as melibiose (the substrate it is specific to)? How specific are the two? If a reaction is catalyzed, the tertiary structure of the enzyme fit the substrate and bound to the substrate. If the structure doesn’t fit, the reaction will not be catalyzed. (Preszler, 2011)

Method: Label 10 fermentation tubes (1-10). Next measure 4mL of your desired sugar, 2mL of your desired enzyme, and 10mL of yeast (or water when needed in replace of yeast) and pour into a beaker and give it a swirl. Then pour the solution into the corresponding fermentation tube. Tip the tube until the closed arm is full of solution and place in the water bath. Record the amount of carbon dioxide produced every five minutes for twenty five minutes. (If the carbon dioxide amount is going beyond the calibration, record the position and reset.)

Treatment| Sugar/Control| Enzyme/Control| Yeast|
One| Lactose| Enzyme A| Yeast|
Two| Melibiose| Enzyme A| Yeast|
Three| Lactose| Enzyme B| Yeast|
Four| Melibiose| Enzyme...
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