Enzyme interactions Flashcards
What is a cofactor?
A substance not made from amino acids but required by an enzyme to function
What two types of cofactors are there?
Permanent part of molecule (prosthetic group) or a temporary part
What is an inorganic cofactor?
Inorganic ions needed by an enzyme to function (e.g. zinc)
What do inorganic ions do?
Either help stabilize the enzyme structure, or take part in the reaction at the AS
What is a coenzyme?
Small inorganic, non protein cofactor
What do coenzymes do?
Help in catalysing reactions, donating or accepting hydrogen ions or phosphate groups
How do coenzymes attach to the enzyme?
can bind permanently near or on AS, or bind temporarily to AS
What is an inhibitor?
Any substance that slows or stops an enzyme catalysed reaction
What is non-reversible inhibition?
When the inhibitor combines permanently with an enzyme, completely inactivating it
What must the cell do when an enzyme is under non-reversible inhibition?
Cell must produce more of the enzyme through activating the gene(s) so that they are transcribed and translated
What is reversible inhibition?
Occurs when inhibitor combines temporarily with an enzyme, can be revered and enzyme activated again
What are the two types of reversible inhibitors?
Competitive, non-competitive
What is competitive inhibition?
Occurs when an inhibitor with same shape as the substrate combines with AS, blocking access for substrate (competes with substrate)
How can competitive inhibition be reversed?
Increase the concentration of substrate
What is non-competitive inhibition?
Occurs when an inhibitor combines with the allosteric site on an enzyme, changing the tertiary structure so that the AS is no longer complementary to the substrate
