3.1.4.2 Enzyme Flashcards
General information about enzyme
Globular protein
Catalysts: a molecule that speeds up, a chemical reaction remain and change
Biological catalyst made up by living cell
Can be used repeatedly - effective
Have a high turn over - catalysed many reaction per second
Simple process Equation
Substrate—> product
Condensation reaction big group
Anabolic reaction : building up molecules
Condensation reaction big group
Anabolic reaction : building up molecules
Hydrolysis big group
Catabolic reaction : breaking molecule down
Which part of substrate bond with enzyme
R group
Why Maltese only catalyse only maltose reaction?
Enzyme are specific to the substrate because they got a specific 3-D tertiary structure therefore a specific active site that only allowed maltose to bind with and form enzyme substrate complex as active site and substrate to have complementary shape
General information about enzyme
It is made in cell
Act Both inside, and outside the cell
Intracellular : catalyse protein synthesis , breakdown old damage cell
Extracellular : enzymes secreted [Exocytosis] from microvilli (villi) to lumen in small intestine for food digestion
Why do we create model of enzyme action?
Help understand the process that can’t really be seen
Two Models of enzyme action
The lock and key model
To induced fit model
How are enzymes use induced fit to catalyse or speed up a reaction?
- Before the reaction, the active site is not complimentary to the substrate.
- As the substrate bind, the active site change shape to better fit/become complimentary to the substrate, forming an enzyme substrate complex
- This stresses or distort the bond in the substrate, causing the reaction to occur and the product to release
Definition of enzyme substrate complex
Intermediate structure formed during an enzyme catalyst reaction in which the substrate an enzyme bind temporarily
Explain why the induced fit model is a better explanation of enzyme action than the lock and key model?
- The lock and key model suggests that the active site of the enzyme is a rigid structure and that the substrate is an exact fit to the active site
- The induced fit model matches current observation that the active site change shape slightly upon binding of the substrate to become a more exact fit (complementary), which then allow the reaction to proceed
How can an enzyme catalysed reaction?
- physical contact
- Complementary
- successful collision (enough energy & suitable orientation)
- energy (higher temperature —> higher kinetic energy) lower activation energy
Definition of activation energy
Minimum energy required for molecule to react
Explain how the active site of an enzyme cause a high rate of reaction
After the substrate bind with the enzyme, it’s changes the shape of active side by induced fit
Enzyme substrate complex cause bond to form / break
Lower activation energy
Factor of affecting enzyme activity
Temperature
P H
Substrate concentration
Enzyme concentration
Enzyme inhibitor (competitive inhibitor/incompetitive inhibitor)
How is rate measured?
How fast the product is made?
How fast a substrate is broken down
Explain how temperature affect enzyme activity
Higher heat energy, more kinetic energy, faster the molecules move, faster the rate of reaction, due to successful collision
Too low: not enough kinetic energy for a successful collision
Too high: denatured, active site changes shape, so enzyme substrate cannot be formed
(As Too much kinetic energy, 3-D tertiary structure active side bonding broke by vibration)
Explain how pH affect the enzyme activity
It interfere (disrupt) with the charges in the amino acid in active site
This cause 3-D tertiary structure, active site bonding broken (hydrogen and ionic bond)
High ph : too many hydrogen ions
Low ph : too many hydroxide ions
Result in denatured of enzyme —> little amount of enzyme substrate complex form —> lower the rate
[different enzyme have different optimum pH]
It is important to buffer the pH make it highly stable and resist change
How is substrate concentration affect enzyme activity?
- lower concentration of substrate —> slow reaction —>fewer collision between the enzyme and substrate ( little molecule available for collision)—> little amount of enzyme substrate complex
- Higher concentration of substrate—> more substrate, molecule, more collision, more successful collision as active site are more likely to be occupied
- too high , no difference, or active site occupied(saturated), rate keep constant
How enzymes concentration affect, enzyme activity?
Lower concentration: active side will become saturated with substrate , unable to work any faster
Higher concentration : more & molecule, More successful collision, as active site is more likely to be occupied
Too high: no effect, constant rate, more than enough enzyme to deal with all substrate (excess)
Competitive inhibitor
Same or similar shape as the substrate
Bind with active site — > enzyme inhibitor complex
Preventing the substrate from binding , preventing reaction to occur
It is reversible / non-permanent
Higher concentration of substrate : flood/ out compete inhibitor (knock them out of the active site) —> substrate, collide, and bind with enzymes (graph : meet)
Noncompetitive inhibitor
Bind to the enzyme allosteric site
Causing 3-D tertiary structure, an active site to changes shape permanently
Substrate can no longer bind /no longer complimentary to active side
It is inreversible /permanent
Higher concentration of substrate : no effect
