cofactors

• Some enzymes can only function properly if another non-protein substance is present to “help"

  For example, some enzymes are inactive until they combine with a non-protein substance that changes their tertiary structure (allowing the active

  site to bind correctly with the substrate)

  These substances are broadly known as cofactors
• cofactor – A Non organic, non-protein group essential for enzyme action

  •Cofactors can be permanently bound or only present in reactions

  •Cofactors can also activate precursor enzymes
• •Coenzyme – An organic, non-protein group essential for enzyme action

  
• Cofactors are non-organic groups used in enzyme action. These are often obtained through diet in the form of minerals such as chlorine, calcium or zinc ions.

  Chlorine is a cofactor used by amylase in the break down of starch into glucose. It works by changing the tertiary structure of the enzyme’s active site allowing it to form the correct complimentary shape for the substrate to bind.

  Zinc is another cofactor. It permanently bonds to carbonic anhydrase which is used to metabolise carbon dioxide. It works by helping to encourage the first step of this reaction.
• NAD and Coenzyme A are both coenzymes. They are organic molecules derived from vitamins which are essential for enzyme action.

  NAD is derived from Vitamin B3 and is used to transfer hydrogen ions between molecules involved in respiration.

  Coenzyme A is derived from Vitamin B5 and is essential in the breakdown of fatty acids and carbohydrates in Respiration as it carries molecules between enzymes during this vital process.
• H+ ions can also be used as cofactors (in the form of changing pH) for example protease would be dangerous outside the stomach so is made as a precursor enzyme pepsinogen. When it enters the stomach the decreased pH (increase in H+ ions) causes the enzyme to change shape and activate, allowing it to break down proteins.
• •Cofactors are non-protein substances (i.e. not made from amino acids) that enzymes require in order to function properly.

  •Cofactors can be a temporary part of the enzyme or a permanent part
• •Coenzymes are organic non-protein cofactors.

  •Coenzymes contribute to enzyme-catalysed reactions by accepting or donating hydrogen ions or chemical groups (e.g. phosphate groups)