4.1 enzyme note

4.1 enzyme note - Enzymes: Chemical Regulators Enzymes -...

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Enzymes: Chemical Regulators Enzymes - protein catalyst (substance that accelerates certain chemical reactions by lowering the activation energy required for the reaction to proceed without being consumed) - be lowering the activation energy, it allows more molecules to react at any one time - an enzyme can only promote a chemical reaction that could be made to proceed without it; they simply speed up reactions How Enzymes Work Definitions: Substrate -- an atom or molecule that an enzyme interacts with -- a substance on which an enzyme reacts; a reactant in an enzymatically catalyzed reaction -- must fit into and be bound by the enzyme's active site if a reaction is to occur Active Site -- an area of an enzyme that accepts a substrate and catalyzes its reaction with another -- the active site recognizes the substrate by its size , shape , electrical charge , and hydrophobic/hydrophilic nature (determined by its tertiary structure or its quaternary structure if present) Enzymes form temporary chemical compounds with their substrates. These complexes then break up, releasing the products and regenerating the original enzyme molecule for use. The enzyme itself is not permanently altered or consumed by the reaction. Thus, enzymes can be reused . Naming Enzymes - They are usually named by the addition of the suffix "ase" to the name of the substrate acted upon (and sometimes the type of reaction) Example: Sucrose is split by the enzyme sucrase . (substrate) (enzyme) A dehydrogenase removes hydrogen. Models named after the substrate named after the type of reaction
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Induced Fit Model substrate 1 enzyme enzyme substrate 2 enzyme-substrate complex product enzyme + substrate 1 + substrate 2 enzyme-substrate complex enzyme-substrate complex enzyme + product(s) Cofactors and Coenzymes
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Some enzymes consist only of protein Some enzymes consist of 2 components" 1. a protein apoenzyme holoenzyme 2. an additional chemical compound cofactor ( holoenzyme = cofactor + apoenzyme) Cofactors - small ions or molecules that must be present for a reaction to occur - may be permanently bound to a site or may bind loosely with the substrate during catalysis - some cofactors are called coenzymes ; others are called carriers - Example of Cofactors 1. metal ions - inorganic substances such as minerals required in enzymatic activities - examples -- iron (in cytochrome molecules (carriers proteins)) -- copper -- zinc -- magnesium 2. organic (C-containing), nonpolypeptide (nonprotein) compound ; called a coenzyme - cofactors because they bring
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This note was uploaded on 12/06/2009 for the course BIO BLG143 taught by Professor Kimberleygilbride during the Spring '09 term at Ryerson.

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4.1 enzyme note - Enzymes: Chemical Regulators Enzymes -...

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