CHMI 2227 - E.R. Gauthier, Ph.D. 1
CHMI 2227EBiochemistry I
Enzymes:- catalysis
CHMI 2227 - E.R. Gauthier, Ph.D. 2
Enzyme catalysis
CHMI 2227 - E.R. Gauthier, Ph.D. 3
Enzyme catalysisBasic reaction mechanisms
General acid/base catalysis:
Three main types of catalysis are found:
Covalent catalysis: Metal ion catalysis:
CHMI 2227 - E.R. Gauthier, Ph.D. 4
Enzyme catalysisGeneral acid/base catalysis
Chymotrypsin
O
OHR
HOR
+
H
CHMI 2227 - E.R. Gauthier, Ph.D. 5
Enzyme catalysisMetal ion catalysis
H+
CHMI 2227 - E.R. Gauthier, Ph.D. 6
Enzyme catalysisCovalent catalysis
Nucleophile
CHMI 2227 - E.R. Gauthier, Ph.D. 7
Enzyme catalysisRefresher – nucleophiles and electrophiles
CHMI 2227 - E.R. Gauthier, Ph.D. 8
Enzyme catalysis- Enzymes often combine two catalytic strategies
General Acid/base catalysis
Covalent catalysis
CHMI 2227 - E.R. Gauthier, Ph.D. 9
Example of enzyme catalysis1. Chymotrypsin
CHMI 2227 - E.R. Gauthier, Ph.D. 10
Example of enzyme catalysis1. Chymotrypsin
CHMI 2227 - E.R. Gauthier, Ph.D. 11
Example of enzyme catalysisImportance of the catalytic triad
CHMI 2227 - E.R. Gauthier, Ph.D. 12
Example of enzyme catalysis1. Chymotrypsin - specificity
CHMI 2227 - E.R. Gauthier, Ph.D. 13
Example of enzyme catalysis1. Chymotrypsin - specificity
Ser195 Ser195
CHMI 2227 - E.R. Gauthier, Ph.D. 14
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
CHMI 2227 - E.R. Gauthier, Ph.D. 15
Example of enzyme catalysis1. Chymotrypsin - catalysis
CHMI 2227 - E.R. Gauthier, Ph.D. 16
Example of enzyme catalysisSimilarities between different proteases
CHMI 2227 - E.R. Gauthier, Ph.D. 17
Example of enzyme catalysisSimilarities between different proteases
CHMI 2227 - E.R. Gauthier, Ph.D. 18
Example of enzyme catalysis2. Enolase
CHMI 2227 - E.R. Gauthier, Ph.D. 19
Example of enzyme catalysis2. Enolase
CHMI 2227 - E.R. Gauthier, Ph.D. 20
Example of enzyme catalysis2. Enolase
CHMI 2227 - E.R. Gauthier, Ph.D. 21
Example of enzyme catalysis3. Lysozyme
CHMI 2227 - E.R. Gauthier, Ph.D. 22
Example of enzyme catalysis3. Lysozyme
Sugar portion of peptidoglycan
CHMI 2227 - E.R. Gauthier, Ph.D. 23
Example of enzyme catalysis3. Lysozyme
CHMI 2227 - E.R. Gauthier, Ph.D. 24
Example of enzyme catalysis3. Lysozyme
H2O
2