Lecture 9 Protein Structure and Function

Lecture 9 Protein Structure and Function - EXAM II Fall...

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EXAM II Fall term 2011 PROTEIN STRUCTURE AND FUNCTION Lecture Goals 1. What are enzymes? Be able to describe the chemical nature of enzymes and their functions in biochemical reactions. 3. How do enzymes work, and why are they so specific? Be able to provide an overview of what happens as one or more substrates and an enzyme come together so that the catalyzed reaction can occur, and be able to list the properties of enzymes that make their specificity possible. 5. What effects do temperature, pH, enzyme concentration, and substrate concentration have on enzyme activity? Be able to describe the changes in enzyme activity that result when temperature, pH, enzyme concentration, or substrate concentration change. Exam II Lecture #3, W, Oct 19, 2011 Enzymes and Vitamins Reading material, Chapter 19, pp. 593-606 Problem Set 5 (posted on CTools); due Tues, Nov 1st at the beginning of Discussion
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Chemical reactions in our body versus in the laboratory. Reactions in an organism and a laboratory are controlled in very different ways. An organism maintains physiological conditions of constant temperature, solvent, and pH 7.4, and thousands of reactions take place in the body at one time. In a laboratory reaction temperature, solvent, and pH can be varied and occur one at a time. 19.1 Catalysis by Enzymes Enzymes, proteins, are powerful and specific biological catalysts. How do enzymes work? Enzymes (1) accelerate the rates of reactions but (2) the enzymes do not undergo change themselves at the end of the reaction. Enzymes (3) do not affect the equilibrium point of a reaction and (4) cannot catalyze a reaction that is energetically unfavorable. Enzymes (5) decrease the time it takes to reach equilibrium by lowering the activation energy. Enzymes are, with a few exceptions, water-soluble globular proteins which are more complex than simple inorganic catalysts. Due to their size and complexity, enzymes have several ways to interact with reactants (substrates), speed up reactions, and be controlled. Lecture goal #1. What are enzymes? Lecture goal #2. How do enzymes work, and why are they so specific?
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An enzyme contains an active site , a region where a reaction takes place; the active site has a specific shape and chemical reactivity needed to catalyze the reaction. What is the relevance of shape to specificity? What determines the chemical reactivity? A chiral reactant and a chiral reaction site.
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Lecture 9 Protein Structure and Function - EXAM II Fall...

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