1. A LL A BOUT E NZYMES ! By: Ashley Harris,Sharon Mei, Colleen Chasteau

2. W HAT ARE E NZYME AND E NZYMATIC R EACTIONS Def: Enzymes are biological catalysts, mainly proteins, generated by an organism to speed up chemical reactions. They have an active site on which the substrate is attached, and then broken up or joined.

3. L OCK AND K EY M ODEL / I NDUCED F IT German chemist Emil fischer,in 1840,proposed the lock and key model.According to this model both the enzymes and the substrate possess specific complementary geometric shapes that fit exactly into one another.

4. V IDEO 4 Click the image to play the video segment. Video 4 Enzymatic Reactions 2D

5. C OMPETITIVE AND N ON C OMPETITIVE I NHIBITOR In competitive inhibition the inhibitor and the substrate compete for placement in the active site of the enzyme. These inhibitors are said to have the same shape to that of the substrate and prevents the enzyme/substrate complex from forming. In Non competitive inhibition, the inhibitor does not compete with substrate for a place in the active site but however does reduces enzyme activity by binding to another site on the enzyme known as the Allosteric site.

6. E NZYME R EACTION Temperature - too cold the enzyme will still work but slowly, too hot and the enzyme will become denatured. As temperature increases, the kinetic energy of the molecules increases so they move around more, meaning that there are more collisions between the enzymes and substrate molecules and therefore more reactions. pH - different types of enzymes work best in different pH environments. A change in pH interferes with the shape of the enzymes active site (where it bonds and reacts with substrate) and therefore does not fit the shape of the substrate as well so the enzyme is unable to work on the substrate. enzyme and substrate concentration - how many there is of each. Changing the concentrations of enzyme and substrate concentrations will affect the number of collisions between them and therefore the number of reactions. enzyme inhibitors - these are molecules which bind to enzymes, reducing their activity (many drugs are enzyme inhibitors).

7. E XAMPLES OF E NZYMES IN THE BODY Amylase I is activated by chewing and begins the digestive process by converting starch (amylose) to maltose. Amylase II, produced by the pancreas, is only slightly different chemically and continues the process started by the salivary amylase. * Pepsin is secreted as proenzyme pepsinogen by the chief cells of the stomach and activated by hydrogen in the stomach acid, also producing hydrochloric acid at the same time. It functions best in a pH of 1.5-2.0 in order to break bonds between amino acids in proteins, producing short-chain polypeptides and destroying any pathogens that enter with the food. * Trypsin is secreted from the pancreas as proenzyme trypsinogen. It functions best in a pH of 7-8. Trypsin acts on proteins and polypeptides to produce short-chain peptides. It also activates other pancreatic proteinases. * Maltase, sucrase, and lactase are secreted by the mucosal cells of the small intestine and found in the membrane surface of microvilli. They function best in a pH of 7-8. They respectively target the sugars maltose, sucrose, and lactose to produce monosaccharides.