cofactors and coenzymes

Page 1

co factors and co enzymes are essential for enzyme function

some enzymes will only work if there is another no-protein substance bound to them. these non-protein substances are called co factors.

some co factors are inorganic molecules or ions. they work by helping the enzyme and substrate bind together. they don't directly participate in the reaction so aren't used up or changed in anyway. for example, chloride ions (cl-) are co factors for the enzyme amylase

some co factors are organic molecules- these are called co enzymes. they participate int the reaction and are changed by it (they are kind of like a second substrate). they often act as carriers moving chemical groups between different enzymes. they're continually recycled during this process. vitamins are often sources of co enzymes.

if a co factor is tightly bound to the enzyme, its known as a prosthetic group. for example, zinc ions (Zn 2+) are a prosthetic group for carbonic anhydrase (an enzyme in red blood cells, which catalyses the production of carbonic acid from water and co2). the zinc ions are a permanent part of the enzymes active site.