What are cofactors and coenzymes? AS BiologyWatch
Example: Amylase catalyses the breakdown of maltose molecules. This enzyme will function properly only if chloride ions arepresent. Without the chloride ions, amylase cannot catalyse the reaction
Coenzymes: metalloorganic, non-protein molecules that bind before or with the substrate. They can be prosthetic groups if they are found permanently within the enzyme.
Example: The enzyme carbonic anhydrase contains a zinc-based prosthetic group. This enzyme is a vital component in red bloodcells, where it is involved in catalysing the combination of water and carbon dioxide to give carbonic acid. This is animportant reaction that enables carbon dioxide to be transported in the blood
All you need to know is that they are vital for the actual reaction of the enzyme with the substrate. You can think of them as trying to put half a puzzle piece (the enzyme) together with another puzzle piece. They aren't going to fit unless you can find the other half (the cofactor/enzyme), so you won't get a reaction.