Lecture 3 - Levels of protein structure Primary structure...

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Levels of protein structure Primary structure is the sequence of amino acids along the backbone. Secondary structure involves O or N of the peptide bond. Tertiary structure involves the amino acid side chains along the same backbone. Quaternary structure involves two or more protein chains. Why is our knowledge of protein structure relevant to health? Structure is important because it is crucial to function. The substitution of Glu→Val in hemoglobin causes sickle cell anemia, a disease which limits the ability of the tetrameric protein Hb to carry oxygen. The substitution is a chance in primary structure. The side chains of Glu and Val differ considerably in their ability to bond; tertiary structure. A tetramer is composed of 4 subunits; Hb has quaternary structure. Hemoglobin is a conjugated protein; the heme group (see Figure 18.8) contains a Fe2+ to which O2 binds.
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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
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This note was uploaded on 01/27/2012 for the course BIOCHEM 212 taught by Professor Jeannestuckey during the Fall '11 term at University of Michigan.

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Lecture 3 - Levels of protein structure Primary structure...

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