UMass Amherst BIOLOGY 285 - Bio 285 SI Before Exam 2 (5 pages)

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Bio 285 SI Before Exam 2



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Bio 285 SI Before Exam 2

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Pages:
5
School:
University of Massachusetts Amherst
Course:
Biology 285 - Cellular & Molecular Biology
Cellular & Molecular Biology Documents

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Bio 285 SI Before Exam 2 March 6 Mechanism of Enzyme Function Q What do enzymes do to a reaction energy of the graph o They lower the activation energy and the transition state o Peak of graph is transition state lowers o Speeds up rate of reaction Enzymes are catalysts Do we change free energy of reactants and products NO If energy of the reactants is higher than products exergonic o Released energy so molecule is STABLE If energy of products is higher than reactants endergonic o Considered UNSTABLE Enzymes take a substrate form a complex then switch substrate into product then release product o 3 ways to do this Enzyme binds to 2 substrate molecules and orients them precisely to encourage a reaction to occur between them Binding of substrate to enzyme rearranges electrons in the substrate creating partial negative and positive charges that favor a reaction Enzyme strains the bound substrate molecule forcing it toward a transition state to favor a reaction o Enzyme with substrate has higher binding affinity b c wants to let product go needs to hold onto substrate to be able to turn it into product Q pull down assay effective way to look for substrates o Reaction takes a long time so by that time substrate would be product so not useful Enzymes lower the activation energy of a chemical reaction Allostery Regulation of Enzyme Protein Function Allostery when something other than the substrate binds to somewhere other than the active site causes conformational change o Activate enzyme or inhibit enzyme When allosteric enzyme binds changes shape function o Can be positive or negative Ex Hemoglobin o When one molecule of O2 binds to a hem group changes conformation of the other 3 hem groups which then have a higher affinity to O2 Post translational modifications you modifying the protein after protein has been created o Phosphorylation ubiquitination methylation acetylation Post translational modify RTK through phosphorylation Nucleotide binding hydrolysis can lead to



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