BIOL 3510 1st Edition Lecture 3 Outline of Last Lecture I. An Introduction to Proteins and Amino AcidsII. Bonds: Covalent, Polar Covalent, Non-covalent/ForcesOutline of Current Lecture I. The Functions of Different ProteinsII. Enzymes and their actionsa. LysozymeIII. Protein RegulationIV. Antibodies and their usesCurrent LectureProteins IIProteins interact with other moleculesLigand – anything bound by a protein.Binding site – area of a protein that interacts with a ligand – selective binding is mediated by many, non-covalent bonds/forcesProteins have diverse functions such as: speed up the rate of chemical reactions (enzymes), provide support in and outside of cells (like keratin), and function in storage and transport (like hemoglobin).Enzyme = protein that acts as a catalystEnzymatic reactionsThe substrates (ligand) binds to an active site (binding site).Substrate is altered upon binding so that the desired reaction is favored.1. Holds substrates in alignment: envourages reaction2. Re-arranges electrons: stabilizes intermediates3. Alters bond angles: moves towards transition stateThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Example: Lysozymes cleave polysaccharide chains found in bacterial cell wallsSmall molecules covalently attached to proteins increase protein functionality. They are used forfunctions that amino acides cannot perform. -Fe binds oxygen in hemoglobin-Metals near active sites make transient bonds with the substrateRegulation of protein function-Amount of protein-Location of protein-Modification of protein activity by modifying the protein’s shape. 1. Feedback inhibition of allosteric proteins2. Positive regulation of allosteric proteins3. Protein phosphorylation4. Other covalent modifications of proteins5. Binding of GTP6.Binding and hydrolysis of ATPAllosteric proteins undergo conformational changes upon ligand binding which alters their activity. Feedback inhibition occurs when a product of a pathway inhibits an enzyme that acts earlier in the pathway. Enzyme regulation can be positive or negative.Protein phosphorylation can inhibit or stimulate protein function.Kinase- attaches phosphates to serine, threonine, or tyrosine side groups on a target proteinPhosphatase – Removges phosphates from a target proteinExample: cell cycle progression is controlled by phosphorylationOther covalent modifications also affect protein activity. Binding GTP activates GTP-binding proteins. For example, the elongation factor (EF-Tu) undergoes a large conformational change after GTP hydrolysis. Hydrolysis of bound ATP can provide directionality to a series of conformational changes, like myosin walking along an actin microfilament.A combination of different protein modifications and binding partners control protein (complex) assembly and function.Antibodies are useful tools for studying proteins. They recognize specific antigens, can be used for immunoprecipitation, and as molecular tags duing
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