enzymes Flashcards
definition of active site
indented area on the surface of an enzyme molecule, with a shape that is complementary to the shape of a substrate molecule
catalyst definition
chemical that speeds up rate of reaction that remains unchanged and reusable at the end of a reaction
extracellular definition
outside the cell
intracellular definition
inside the cell
metabolic/metabolism definition
chemical reactions that take place inside the cell
product
molecule produced from the substrate molecules. from an enzyme-catalysed reaction
substrate
molecule that is altered by an enzyme-substrate reaction
What is a cofactor
Non protein compound required for enzymes activities to occur. Bind with enzymes and help.
What are the three types of cofactor
Coenzymes
Activators
Prosthetic groups
What are coenzymes
Organic cofactors
Do not bind permanently
Facilitate binding of substrate to enzyme
Many=vitamin derives
What is an activator
Inorganic metal ion
Temporarily bind to enzyme & alter active site
What is a prosthetic group
Cofactor
Permanently attached to enzyme
E.g haemoglobin
What is induced fit model
Structure of enzyme is altered so that the active site pf the enzyme fits around the substrate
How does enzyme conc affect reaction
RoR increases as EC increases bc there are more AS for substrates to bind to. However increasing EC beyond a certain point has no effect on RoR as there are more AS than S so SC becomes limiting factor
Effect of substrate conc on RoR
RoR increases as SC increases bc more ES complexes are formed. However beyond a certain point it has no effect on RoR as EC becomes limiting factor
Effect of temp on RoR
RoR increases up to the optimum temp. If T too high then they can denature as the hydrogen and ionic bonds break from vibration of atoms. This disrupts hydrophobic and hydrophilic interactions and the tertiary structure.
Enzyme definitiom
Biological catalysts that increase RoR by decreasing AE. Large globular proteins consisting of hundreds of amino acids. Have an active site which is specific to a substrate. Remain unchanged at the end of every reaction so can be reused.
What is an inhibitor
Substance which slows down or stops a reaction by affecting the binding of substrate to be enzymes. Can be reversible or irreversible
Describe irreversible inhibitors
Cause protein structure to break causing shape of AS to change, affecting protein activity. E.g cyanide
Describe reversible inhibitors
Bind to AS by hydrogen bonds and weak ionic interactions. Can either be competitive or non competitive
Describe competitive inhibitors
Reversible
Similar structure to substrate
Bind to AS, decrease activity (compete with substrate)
amount of product formed remains same but RoR decreases
Describe non competitive inhibitor
Reversible
Does not bind to AS
Binds to another site on enzyme called ALLOSTERIC SITE
This changes shape of AS and prevents binding of substrate
Example of inhibitors
Drugs e.g penicillin
Fights bacterial infection
Inhibitor of enzyme transpeptidace
How do enzymes work
Substrate molecules bind with the complementary AS forming an ES complex. Enzyme catalyses the breakdown of the substrate into product forming EP complex
