Enzymes Flashcards
Metabolism
The rate at which chemical reactions take place in the body
Turnover number
How many molecules of substrate an enzyme can convert into product per unit of time
Active site
The specific 3D site on an enzyme molecule to which the substrate binds by weak chemical bonds.
Activation energy
The energy needed to start a chemical reaction, by breaking the existing bonds in the molecule.
Optimum temperature
The temperature at which the rate of enzyme-catalysed reactions is highest.
Cofactors
Non-protein molecules which modify the chemical structure of an enzyme so that it may function more effectively
Prosthetic groups
Organic molecules which form a permanent attachment to the enzyme
Coenzymes
Small, non-protein, organic molecules, not permanently attached to the enzyme and help enzymes and substrates bond with each other.
Activators
Inorganic metal ions which form a temporary attachment to the enzyme and alter the active site so a reaction is more likely to take place
Inhibitor
A substance that slows down or stops the rate of enzyme-controlled reactions
Metabolic pathway
A series of enzyme controlled reactions
Multi-enzyme pathway
Where each reaction in a metabolic pathway is catalysed by a different enzyme
End product inhibition
Where the multi-enzyme pathway is controlled by the end product
Negative feedback
The output from a system affects the input
Anabolic reaction
Building up of molecules e.g. protein synthesis
Catabolic reaction
Breaking down of molecules e.g. digestion
Enzyme specificity
An enzyme is specific for its substrate
Enzyme-Substrate complex
Temporary structure formed during an enzyme-catalysed reaction in which the substrate and enzyme temporarily bind so that the substrate is close enough to react
Competitive inhibition
A reduction in the rate of enzyme-controlled reactions by a molecule or ion that has a complementary shape to the active site, similar to the substrate, and binds to the active site, preventing the substrate from binding.
Allosteric site
A site other than the active site
Non-competitive inhibition
An atom, molecule or ion that reduces the rate of an enzyme by binding at a position other than the active site, altering the shape of the active site and preventing the substance from successfully binding to it.
Immobilised enzyme
Enzyme molecules bound to an inert material, over which the substrate molecules move.
Biosensor
A device that combines a biomolecule, such as an enzyme, with a transducer, to produce an electrical signal which measures the concentration of a chemical.
Denaturation
The permanent damage to the structure and shape of a protein molecule e.g. an enzyme, due to, for example, high temperatures of extreme pH
Inactivation
Reversible reduction of enzyme activity at low temperature as molecules have insufficient kinetic energy to form enzyme-substrate complexes
Limiting factor
A factor where increasing its value increases the rate of reaction
Saturated enzyme
When all the enzyme’s active sites are occupied by substrate.
