Lecture 7 - Enzymes and Catalytic Strategies

Lecture 7 - Enzymes and Catalytic Strategies - Chapter 9 -...

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Chapter 9 - Catalytic Strategies Covalent catalysis General acid-base catalysis Metal ion catalysis Catalysis by approximation 1
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1. Activate H 2 O or other nucleophile 2. Polarize the peptide carbonyl group 3. Stabilize a tetrahedral intermediate Common Features in Proteases 2
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Protease that cleaves peptides at the carboxy terminus of tryptophan, tyrosine, phenylalanine and methionine Specificity of Chymotrypsin 3
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Active site modification of Chymotrypsin 4
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The catalytic triad of chymotrypsin 5
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Chymotrypsin active site formation via folding: The Protein scaffold is required for catalysis 6
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Substrate binding pocket: Protein folding is required for catalysis 7
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Know the roles of these active site residues in chymotrypsin: Histidine 57 Aspartate 102 Serine 195 Glycine 193 PDB code: 7gch. Protein folding is required for catalysis 8
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The catalytic cycle of chymotrypsin 9
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Formation of Tetrahedral Intermeidate 10
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Enzyme The transition state and the tetrahedral intermediate are stabilized by the oxyanion hole of chymotrypsin 11
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Formation of Acyl Enzyme 12
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Loss of Amino- peptide 13
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Binding of Water 14 Water moves in to replace serine on the acyl enzyme to form a second tetrahedral intermediate
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Second Acyl Enzyme 15
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Second Tetrahedral Intermediate breaks down to release the carboxyl terminal peptide 16
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The hydrophobic pocket of chymotrypsin is a major specificity determinant of the enzyme 17
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Lecture 7 - Enzymes and Catalytic Strategies - Chapter 9 -...

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