C1.1 Enzymes Flashcards
Metabolism
A complex network of interdependent and enzyme catalyzed chemical reactions occuring in living organisms
Anabolic reactions
Synthesis of polymers from smaller monomers
Anabolic & catabolic acronym
Anabolic = assemble, catabolic = cut down
Effect on active site in - Catabolic Reactions
Enzymes active site affects the bonds in the substrate so they are easier to break. to smaller molecules
Enzymes
Biological catalysts which speed up the rate of a reaction without being used up themselves
Enzyme Info
- reduce activation energy of a reaction
- can work intracellular and extracellular
- globular proteins
- tertiary structure
Enzyme Mechanism
specificity = enzyme substrate complex = enzyme product complex = release of product
Lock-and-key assumptions
assumes the active site of an enzyme is rigid in its shape
Induced fit
suggests the active site is flexible and only assumes catalytic conformation after the substrate molecules bind to the site
Enzyme immobilisation
Enzymes can be immobolised by being embeded in the membrane of cells
Denaturation
An irrevsersible change to a proteins active site
How enzymes operate in anabolic reactions
- enzymes hold substrates close together
- reduce repulsion
- bonds more easily
How enzymes operate in catabolic reactions
- enzymes active site puts strain on bonds
- fitting the substrate into active site puts strain on bonds
- easier to break
activation energy
energy needed to start a reaction
How PH affects enzyme activity
- a change in pH from the optimum affects the charges of the enzyme proteins
- alters 3e structure
- denaturation
- goes up and rapidly down
How substrate concentration affects enzymes rate of reaction
- increased substrate concentration leads to increased reaction rate as more ESC are formed
- until saturation point
- increases sub. conc. will not increase rate of reaction anymore as all enzymes active sites are occupied
- no more ESC
- plateaus
Metabolic pathway
Any chain or cycle of linked reactions catalysed by enzymes
competitive inhibitor mechanism
- similar shape to substrate
- binds to active site
non competitive inhibitor mechanism
- binds to allosteric site
- substrate no longer fits
Type of non competitive inhibition
End Product Inhibition
In order to control metabolic pathways the end product of the pathway can sometimes inhibit the activity of the first enzyme in the pathway
(avoids excessive prodcution & build up)
competitive inhibitor
A mechanism in which the inhibitor competes with the substrate to bond with the actuve site
non competitive inhibitor
A mechanism in which the inhibitor to an allosteric site away from the enzymes active site
Metabolic rate
Amount of energy needed by that organism in a given time period
mechanism (suicide) based inhibition
inhibitor binds permanently to the active site
ex: anti cancer, anti HIV, antibiotic
Inactive precursors
types of enzyme that have an inhibitor on it, this it only works in certain coniditions
Inactive precursor
Protease
- an inactive precursor
- means that it only works under acidic PH conditions
- to prevent protein degration
Why when substrate conc. increase; rate increase?
More frequent collisions
competitive inhibitor - descripitive graph
- slows down rate of reaction as it competes for active site
- has a similar shape to substrate
- binding is reversible
- as substrate conc. increases; more binds to active site than competitor = reaction rate increases
- plateaus as all active sites will be at full capacity
catabolism
breaking down complex molecules into smaller monomers
Importsnce of enzymes in metabolism
- lower activation energy
- increase rate of reaction
- end product inhibition can control metabolic pathways
- specific enzyme for each substrate
Outline Lock and Key model
- explains specificity of enzyme-substrate
- the substrate (key) fits into enzymes active site (lock)
- active site can only be changed through temperature & pH changes => substrate cannot bind
Outline induced fit model
- as ESC is formed; active site changes to allow substrate to bind
- substrate induces active site to change
- bonds weakend in the substrate (easier to break)
- easier to break bonds = lowers activation energy
- opportunities for wider substrate specificity
How do bacteria develop resistance to penicillin?
- modifying the structure of their transpeptidase enzymes
- prevents the irreversible binding of penicillin to the active site.
