Enzyme Cofactors and
Coenzymes
Cofactors
Some enzymes require an additional non-protein component to function properly and
cannot function alone
Cofactors are small molecules that ensure an enzyme-catalysed reaction takes place
Two types: pure cofactors and coenzymes
Pure Cofactors
Inorganic – minerals or metal ions
Help enzymes function properly
More involved and assist in catalysis
Some bind temporarily to ease the formation of an ESC by:
o Binding to substrate to form a co-substrate with the correct shape
o Binding to the active site to form the correct shape
o Affecting the charge in either the enzyme or substrate which makes the
temporary bons in an ESC easier to form
Coenzymes
Organic – vitamins or vitamin derivatives
Carrier molecules and only carry substances to/from enzymes
Temporarily bond to the enzyme either just before or at the same time as the substrate
Chemically changed by the reaction and must be recycled by a different enzyme
Prosthetic Groups
Cofactors which are permanently bonded to an enzyme’s active site
Vitamins
B-vitamins are the precursors of coenzymes
A lack of vitamins can lead to deficiency which can result in disease
Coenzymes
Cofactors
Some enzymes require an additional non-protein component to function properly and
cannot function alone
Cofactors are small molecules that ensure an enzyme-catalysed reaction takes place
Two types: pure cofactors and coenzymes
Pure Cofactors
Inorganic – minerals or metal ions
Help enzymes function properly
More involved and assist in catalysis
Some bind temporarily to ease the formation of an ESC by:
o Binding to substrate to form a co-substrate with the correct shape
o Binding to the active site to form the correct shape
o Affecting the charge in either the enzyme or substrate which makes the
temporary bons in an ESC easier to form
Coenzymes
Organic – vitamins or vitamin derivatives
Carrier molecules and only carry substances to/from enzymes
Temporarily bond to the enzyme either just before or at the same time as the substrate
Chemically changed by the reaction and must be recycled by a different enzyme
Prosthetic Groups
Cofactors which are permanently bonded to an enzyme’s active site
Vitamins
B-vitamins are the precursors of coenzymes
A lack of vitamins can lead to deficiency which can result in disease
