Transcript Enzyme
Fig. 6.5a Fig. 6.5b Fig. 6.5 Enzymes bring substrates close enough, and hold them so that they are able to react at a much lower temperature Fig. 6.6a Hydrolysis: Fig. 6.6b Synthesis Fig. 6.7a Fig. 6.7b Enzyme-Substrate complex Fig. 6.7 Fig. 6.7a Enzyme is recycled-ready to bind to another substrate Fig. 6.8b What Effect will Temperature have on Enzyme Rate? Fig. 6.8a Fig. 6.8 Fig. 6.9 • Enzymes work best at a CERTAIN pH • Stomach enzymes work best in an acidic environment (pH 2-3) • Small intestine enzymes work best in a basic or alkaline environment (pH 7-9) • It is incorrect to say low pH denatures enzymes—as this is not true in the stomach • Each enzyme has its own optimum pH • Below or above the optimum, the enzyme will alter its’ shape, and therefore its’ ability to function • The further away from optimum, the lower the ability to function Fig. 6.10 Fig. 6.10a Fig. 6.10b • COMPETITIVE INHIBITION: Lowers the reaction rate as the active site gets “filled-up” by something other than the substrate. Often, this something is the product. • NON-COMPETITIVE INHIBITION: Also lowers the reaction rate, but by something that binds to the enzyme—at some other (allosteric) site that alters the enzyme—now, it is no longer able to fit with the substrate. Often these NCI’s are the products, from a metabolic pathway much further on, or are unwanted POISONS such as Cyanide. • FEEDBACK INHIBITION When the active site is prevented from combining with the substrate, INHIBITION occurs This can be a very effective way of controlling reaction rates. In some reactions, the PRODUCT competes with the substrate. High Product means lower reaction rate! In a Metabolic Pathway, The end product may be substantially different—It binds to the enzyme in ANOTHER LOCATION, called an allosteric site. This alters the shape of the enzyme— the active site also changes, and the reaction rate lowers. Fig. 6.p109 • VITAMINS AND MINERALS—What do these things have to do with enzymes? • Cofactors—enzyme “helpers” Many cofactors are minerals such as Cu, Zn, or Fe required in small amounts by our bodies • Coenzymes are also helpers, but are larger, organic, non-protien molecules commonly called VITAMINS. These too, are obtained from our diet. Fig. 6.p113 R E M E M B E R T H E S E Fig. 6.p113a Fig. 6.p113b Fig. 6.p113c Fig. 6.p113d