Biomolecules Lecture_9

Biomolecules Lecture_9 - Biomolecules and Metabolism...

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Lecture 8 - Enzymes Biomolecules and Metabolism
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Overview Enzymes - Classification - Regulation - Mechanism - Proteases - Kinetics - Assay
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10 Quick Facts! 1. Many enzymes consist of 2 parts Protein portion: apoenzyme Non-protein portion: cofactor 2. Can accelerate biochemical reactions by a factor of 10 6 -10 12 3. Co-factor may be a metal ion (Fe, Mg, Zn, or Ca) or an organic molecule or “co-enzyme” (NAD/NADP) located within the enzyme’s active site 4. Co-enzymes are often derived from vitamins 5. Very specific and efficient 6. Subject to a variety of cellular controls. All cellular reactions involve enzymes! Classification
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10 Quick Facts! 7. Not consumed by the reactions they catalyze 8. Do not alter the equilibrium (direction) of a reaction 9. Some RNA molcules (ribozymes) also display catalytic activity 10. Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease enzyme activity. Activators are molecules that increase activity. Classification
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Nomenclature 1. The International Union of Biochemistry and Molecular Biology have developed a naming convention for enzymes - the EC system. 2. Each enzyme is described by a sequence of 4 numbers (it’s EC number) 3. The first number broadly classifies the enzyme based on its mechanism. For example: EC1 Oxidoreductases: catalyze redox reactions EC2 Transferases: transfer a funcional group EC3 Hydrolases: hydrolysis of a bond EC4 Lyases: non-hydrolytic bond cleavage EC5 Isomerases:molecular isomerization EC6 Ligases:join two molecules covalently Classification
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Metabolic pathways can be linear (e.g. glycolysis) or cyclic (e.g. TCA cycle) Linear: A B C D E1 E2 E3 Cyclic: A B C D E1 E4 E3 E2 Enzymes in Metabolism Regulation
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Enzymes in Metabolism 1. May also have ‘branched pathways’ 2. Product of one reaction is the substrate for the next 3. Function in both catabolism and anabolism 4. May be the reverse of each other 5. Control reactions are irreversible Regulation
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This note was uploaded on 01/05/2010 for the course FSH BT taught by Professor Ianmarison during the Spring '09 term at Dublin City University.

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Biomolecules Lecture_9 - Biomolecules and Metabolism...

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