Download presentation
Presentation is loading. Please wait.
Published byWinfred Cameron Cole Modified over 5 years ago
1
An Introduction to Metabolism and Enzymes
Substate Active site Enzyme
2
Metabolism Is the totality of an organism’s chemical reactions
3
Catalase
4
Activation energy-barrier to reaction
5
Activation energy
6
Mechanism of enzyme reaction
The substrate is the reactant an enzyme acts on The enzyme binds to its substrate, forming an enzyme-substrate complex
7
The catalytic cycle of an enzyme
Substrates Products Enzyme Enzyme-substrate complex 1 Substrates enter active site; enzyme changes shape so its active site embraces the substrates (induced fit). 2 Substrates held in active site by weak interactions, such as hydrogen bonds and ionic bonds. 3 Active site (and R groups of its amino acids) can lower EA and speed up a reaction by • acting as a template for substrate orientation, • stressing the substrates and stabilizing the transition state, • providing a favorable microenvironment, • participating directly in the catalytic reaction. 4 Substrates are Converted into Products. 5 Products are Released. 6 Active site Is available for two new substrate Mole.
8
The active site can lower an EA
The active site can lower an EA barrier by Orienting substrates correctly Straining substrate bonds Providing a favorable microenvironment Covalently bonding to the substrate
9
Reaction pathway
10
3D / tertiary structure of an enzyme
11
Binding sites of an enzyme
12
Specificity-lock and key hypothesis
13
Induced Fit model of enzyme action
14
Induced fit hypothesis
Induced fit of a substrate brings chemical groups of the active site into positions that enhance their ability to catalyze the chemical reaction
15
Effect of Enzyme concentration
16
Effect of Substrate concentration
17
Effect of temperature
18
Effects of Temperature
Each enzyme Has an optimal temperature in which it can function Optimal temperature for enzyme of thermophilic Rate of reaction 20 40 80 100 Temperature (Cº) (a) Optimal temperature for two enzymes typical human enzyme (heat-tolerant) bacteria
19
Optimal pH for different enzymes
Rate of reaction (b) Optimal pH for two enzymes Optimal pH for pepsin (stomach enzyme) Optimal pH for trypsin (intestinal enzyme) 1 2 3 4 5 6 7 8 9
20
Effect of pH on enzyme
21
Cofactors -- enzyme helpers
Are nonprotein enzyme helpers—can be either inorganic or organic Coenzymes Are organic cofactors
22
Co-enzyme e.g. NAD+ NAD+ helps by accepting H removed from substrates by the enzyme dehydrogenase
23
Denaturation and renaturation of enzyme
24
Denaturation and renaturation of enzyme
25
Enzyme Inhibitor_types
26
Competitive inhibition
27
Competitive inhibition
28
Competitive inhibition–e.g. sulphonamide
29
Non competitive inhibition
30
Com vs non comp inhibition
31
End product inhibition –helps regulate enzyme activities
32
End product inhibition
33
End product_cellular respiration
34
Allosteric activator
35
Allosteric inhibitor
36
Allosteric regulation
Is the term used to describe any case in which a protein’s function at one site is affected by binding of a regulatory molecule at another site
37
Specific Localization of Enzymes
Within the cell, enzymes may be Grouped into complexes Incorporated into membranes Contained inside organelles 1 µm Mitochondria, sites of cellular respiraion Figure 8.22
40
Bacteria in Hot springs
41
Enzyme application_thermophilic
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.