Key and lock theory of induced fit

1
Key and lock theory of induced fit

2
Endopeptidase
3
Exopeptidase
Carboxypeptidase
Aminopeptidase
4
Proteolytic activation of zymogens
Trypsinogen
Chymotrypsinogen
Trypsin
p - Chymotrypsin
a - Chymotrypsin
Trypsin inhibitor
Inactive trypsine
5
Chymotrypsinogen
1..245
Trypsin
p-Chymotrypsin
16..245
1..15
Chymotrypsin
a-Chymotrypsin
16.146
149245
1.13
6
Chymotrypsin hydrolysis of peptide and ester
bonds
Hydrolysis of peptide bonds
Hydrolysis of ester bonds
7
Substrate specificity of Chymotrypsin

• Phe
• Typ
• Trp
• Met

8
Ser195 OH of chymotrypsin reacts with DIPF
CH2OH
CH2
Ser 195
Ser 195
9
Kinetics of chymotrypsin catalysis (measured
with synthetic substrate)
10
Kinetics of chymotrypsin catalysis (measured
with synthetic substrate)
A
Steady state
Burst phase
Time milisecundum
11
Two stages of the enzyme action
Enzyme
Acyl-enzyme
Enzyme
12
Chymotrypsin active site its function
13
Hydrolysis of peptide bond by chymotrypsin
14
Hydrolysis of peptide bond by chymotrypsin
Acyl enzyme intermedier
Acyl enzyme intermedier
Tetrahedral - intermedier
15
Hydrolysis of peptide bond by chymotrypsin
16
Homolog enzymes

• Chymotrypsin Phe, Tyr, Trp, Met
• Trypsin - Arg, Lys
• Elastase amino acids with short side chain
  residues ie. Ala, Ser
• Thrombin Fibrinogen, V, VIII, PC
• Plasmin - Fibrin,

17
Substrate bingind site S1 of chymotrypsin,
trypsin elastase
O
O
Asp 189
Val 216
Val 190
Chymotrypsin
Trypsin
Elastase
18
Cystein, aspartyl metalloproteases

• Papain isolated from papaya
• Nucleophyl attack on peptide bond
• Cathepsins immunsystem
• Caspases - apoptoses

19
Cistein, aspartyl metalloproteases

• Asp protonated
• Asp deprotonated
• H2O
• Renin
• Pepsin

20
Cistein, aspartyl metalloproteases

• Bacterial termolysine
• Carboxypeptidase A
• Zinc proteases (matrix metalloproteinases MMP)
• MMP tissue degradation and remodelling

21
Cholinerg synapsis
Presynaptical membrane
Postsynaptical membrane
22
Acetylcholine esterase

• Synaptic cleft
• Bound to collagen GAG network
• Hydrolysis of Acethylcholine
• a2b2
• Turnovernumber 25000 / sec

Acetilkolin receptor
23
Catalytic mechanism of acetylcholine esterase
24
Organic phosphate inhibitors of acetylcholine
esterase

• Sarin Metro of Tokyo
• Tabun
• extremely toxic substance
• it is classified as a weapon of mass destruction
• Parathion pesticide
• Labelled DIFP
• 12000 / mm2 receptor/mouse diafragma

25
Carbamoylation of Ser-OH in acetylcholine esterase
Physostigmin (Eserin)
Slow hydrolysis of carbamoyl-enzyme intermedier
Ordeal In witchcraft trials
26
Carbamoylation of Ser-OH in acetylcholine
esterase by neostigmin
Neostigmin
Slow hydrolysis of carbamoyl-enzyme intermedier
it inhibits acetylcholine esterase,
acetylcholine increase Decrease in intraocular
pressure
27
Dekametonium bounds to receptor Constant
depolarisation
Succinylcholine slow hydrolysis Pseudocholine
esterase
28
Zymogens of pancreas
29
Enteropeptidase
Trypsin
Trypsinogen
Proelastase
Procarboxypeptidase
Elastase
Carboxypeptidase
Prolipase
Lipase
Cymotrypsinogen
Cymotrypsin