Enzymes Flashcards
How can you measure the course of enzyme catalyzed reactions?
Measuring time taken for reaction to occur, measuring rate of reaction, measuring concentration of product
How can you impact the RoR of a catalyised reaction?
pH, temp, concentration of enzymes or substrate, presence of inhibitors
At optimum temperature?
Ek increases, more successful collisions between enzyme and substrate, more E-S complexes formed
pH at optimum?
Charge of active site is complementary to charge of substrate, more successful collisions, more ES complexes
Minor pH change?
Small reversible change to enzyme structure, H/OH ions cause charge of active site to repel substrate
Extreme pH changes?
H/OH ions interfere with ionic bonds (excess H or OH are attracted to their complementary charges in R groups neutralising them.) Ionic bonds break (and hydrogen), unravel tertiary structure
how does a competitive inhibitor reduction the rate of reaction?
The inhibitor competes with the substrate to bind to the active site
where do non competitive inhibitors bind?
allosteric sites
what is cyanide an inhibitor for?
cytochrome oxidase, found in the inner mitochondrial membrane, stops the sequence of reactions that produces ATP
Cofactor?
Non-protein chemical that helps/ is necessary for a biological chemical reaction
Types of cofactor?
Cofactor: relatively small chemical, normally inorganic
Coenzyme: Large organic molecule
Prosthetic group: permanent part of the enzyme structure
example of cofactor?
NAD, large organic molecule which temporarily binds to respiration enzymes. Transfer H atoms from one molecule to the next
what is meant by enzymes being specific?
any individual enzyme can only catalyse one reaction, only one substrate can fit
more advantages of immobilised enzymes?
high temp would denatured other unwanted enzymes/ kill contaminating microorganisms
Can make more product/ make product faster at higher temperature.
Enzymes can be easily added or removed to control RoR
Can be reused
Dont contaminate product
Disadvantages of immobilised enzymes?
substrate needs to diffuse through gel/membrane
smaller SA of enzyme
Enzyme is at a lower concentration when immobilised
immobilised have low Ek
Immobilization can affect active site so fewer E-S complexes
Immobilised enzymes?
Enzymes fixed to an inert matrix/ insoluble agent through which the substrate flows/diffuses
uses of immobilization?
measuring blood sugar in diabetics, producing lactose free milk, in biosensors
bio sensor?
instrument that measures a SPECIFIC metabolite in a mixture of molecules by converting energy into an electrical signal
what are the pros of using biosensors?
They give quantitative data, and they can detect very small concentrations of molecules:sensitive, they can detect a single type of molecule in a mixture: specific
methods of immobilising enzymes?
Fix in gel beads/ membrane or cellulose fibres
is non competitive inhibition permanent?
many are permanent but those involved in control of metabolic pathways are reversible
example of competitive inhibition
malonic acid inhibits succinate which breaks down succinc acid into fumaric acid
metabolism?
summer of all of an organisms chemical processes, comprising anabolic and metabolic pathways
Metabolic pathway?
A sequence of enzyme controlled reactions in which a product of one reaction is a reactant in the next
Inactivation?
A small reversible reduction in enzyme activity e.g at low temperatures or slightly varied pH
Example of enzyme with highest turn over number?
Catalase: breaks down toxic waste, hydrogen peroxide
higher RoR wit immobilised enzymes in beads?
Use smaller beads= larger surface area= substrate has easier access to enzyme molecule
Effect of temperature on a free enzyme compared to immobilised?
IE has a greater range of optimum, IE denatured at a greater temperature, IE has a higher RoR at lower temperatures
