Immobilising enzymes

Immoblising enzymes refers to a technique where the enzymes are held seperate from the reaction mixture.

Substrate molecules bind to the enzyme molecule and the products that are formed go back into the reaction mixture.

This means that the product created does not need to be removed from the reaction mixture which can be costly. 

Enzymes are seperated from the reaction mixture and so there are less costs involved in purification of the product. 

Enzymes are immediately available to be reused which is particularly. 

Enzymes are more stable as the immobilising matrix  them protects the enzyme molecule. 

Immoblising enzymes is more costly to set up because additional time, equiptment and materials need to be used. 

Immobilised enzymes can be less active as they don't freely mix with the substrate, so the rate of reaction may be reduced. 

There four possible methods for immoblising enzymes one is Adsorption:

Enzymes are mixed with an immobilising support and bind to it due to non covelant bonds e.g ionic bonds. 

Examples of absorbing agents include glass beeds, clay and purous carbon. 

Absorption can give high reaction rates however leakage may take place as bonds between the support are not very strong.

Enzymes are cross linked to eachother using a cross linking agent and covalently bound to an insoluble support. 

The methods don't immobilise a large nuumber of enzymes but the covalent bonds are very strong and so there is very little leakage. 

Enzymes can be trapped for examle in a network of cellulose fibres. 

They are not bound to another molecule so their active site remains unaffected. 

Reaction rates can be reduced as the substrate needs to travel through the trapped barrier. 

The substrate and product can pass through the barrier but the enzyme cannot.

The enzyme is seperated from the reaction mixtureby a partially permeable membrane. 

Substrate and product molecules are small enough to pass through the membrane but the enzymes cannot. 

Leakage of the enzyme is unlikley and the active site is unchanged, however the rate of reaction may be slowed as the enzyme is physically seperated from the reaction mixture.