CHMI 2227 - E.R. Gauthier, Ph.D. 1 CHMI 2227E Biochemistry I Enzymes: - catalysis.

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CHMI 2227EBiochemistry I

Enzymes:- catalysis

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Enzyme catalysis

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Enzyme catalysisBasic reaction mechanisms

General acid/base catalysis:

Three main types of catalysis are found:

Covalent catalysis: Metal ion catalysis:

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Enzyme catalysisGeneral acid/base catalysis

Chymotrypsin

O

OHR

HOR

+

H

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Enzyme catalysisMetal ion catalysis

H+

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Enzyme catalysisCovalent catalysis

Nucleophile

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Enzyme catalysisRefresher – nucleophiles and electrophiles

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Enzyme catalysis- Enzymes often combine two catalytic strategies

General Acid/base catalysis

Covalent catalysis

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Example of enzyme catalysis1. Chymotrypsin

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Example of enzyme catalysis1. Chymotrypsin

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Example of enzyme catalysisImportance of the catalytic triad

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Example of enzyme catalysis1. Chymotrypsin - specificity

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Example of enzyme catalysis1. Chymotrypsin - specificity

Ser195 Ser195

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Example of enzyme catalysis1. Chymotrypsin - catalysis

Catalytic triad

Substrate

C-ter part of the protein

N-ter part of the protein

Peptide bond cleavage

Enzyme regeneration

Covalent intermediate

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Example of enzyme catalysis1. Chymotrypsin - catalysis

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Example of enzyme catalysisSimilarities between different proteases

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Example of enzyme catalysisSimilarities between different proteases

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Example of enzyme catalysis2. Enolase

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Example of enzyme catalysis2. Enolase

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Example of enzyme catalysis2. Enolase

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Example of enzyme catalysis3. Lysozyme

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Example of enzyme catalysis3. Lysozyme

Sugar portion of peptidoglycan

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Example of enzyme catalysis3. Lysozyme

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Example of enzyme catalysis3. Lysozyme

H2O

2