Application of enzymes Specification ref: Text book ref:- Chapter 7 Page 113

Why use enzymes? Properties of enzymes: Very sensitive – can measure tiny concentrations of substances Specific – will only respond to a particular substance

Enzymes speed up the rate of reaction BUT Function at low temperatures and mild conditions

SO No need for expensive equipment or high temperatures or pressures THE PROCESS IS CHEAPER

BUT Enzymes are expensive Although not used up in a reaction, separation from product is expensive and time consuming

Immobilized Enzymes Enzyme is attached to an insoluble material which holds the enzyme in place during a reaction

Advantages The enzyme can be reused Enzyme does not contaminate the product

Enzyme does not vibrate when temperature rises so can withstand high temperatures (thermostable)

Enzyme structure is more stable due to bonds with the insoluble material so can withstand extremes of pH

Use of immobilized enzymes Sweeteners Enzyme : glucose isomerase Converts glucose into fructose

Advantages Fructose twice as sweet as sucrose so less is needed Cheap to produce as large quantities of glucose can be obtained from starch

Methods of Immobilising Enzymes Adsorption onto an insoluble matrix - collagen Held in a gel Trapped in a microcapsule eg alginate beads

Held within a selectively permeable membrane Attached to cellulose fibres Covalent bonding to a binding compound

Other uses of immobilized enzymes To analyse solutions for the presence of certain compounds Biosensors

Biosensors : Have a biological recognition layer This contains an enzyme which binds to specific molecule Producing a measurable chemical change

Chemical change is converted into an electrical signal by a transducer Strength of signal is equivalent to the concentration of substance

Example: Monitor blood glucose levels during surgery Enzyme = glucose oxidase Glucose + O 2 glucuronic acid + H 2 O 2

Enzyme is associated with a platinum oxygen electrode – measures oxygen concentration. As glucose reacts with oxygen the level will fall. This change in oxygen concentration is detected by the platinum electrode

SO The greater the glucose concentration The more the oxygen level will fall Producing a larger signal

Advantage of Enzyme Biosensor compared to Benedicts Test Specific Easy to use Portable No colour confusion Quantitative Sensitive

Other uses of enzymes in industry Brewing Baking Textile processing Washing powders

Brewing

Starch is main source of carbohydrate Amylase and maltase from barley seeds, hydrolyses starch to maltose then to glucose Yeast ferments these sugars

By adding more of these enzymes poor quality seed can be used Other, cheaper sources of starch can be used

Baking

Fungal amylases, which break down starch, can provide sugar to feed yeast during fermentation

Baking The texture of bread is due to the branched structure of starch Staling is due to the branches breaking down Amylase clips the branches and stops bread going stale

Textiles

Textiles - Desizing Size is the name given to the substance that is applied to the warp thread before weaving It forms a coating around the surface of the thread which provides lubrication & prevents the breakage of warp thread during weaving Starch is often used as a ‘size’

Amylase removes starch ‘size’ It specifically hydrolyses starch but does not affect cellulose

Stone washing Stone washing without stones!! Wash jeans with pumice stones – damage cloth Cellulases used to produce same effect without damage to cloth

Washing powder

‘Biological’ washing powder contains enzymes Protease to break down protein stains Amylase for removal of starch soiling Lipase to break down fats and oils Cellulase to help keep cotton looking new

Isolating enzymes from microorganisms Microorganisms are grown in a fermenter and produce enzymes Provide nutrients – Carbon as carbon dioxide Nitrogen as ammonium ions Sulphur as sulphates

Aseptic conditions Contaminating bacteria – Produce other / unwanted products So more downstream processing needed Use the nutrients which lowers the yield

Some enzymes are released from the cells Extracellular enzymes

Some enzymes remain inside the cell Intracellular enzyme

DOWNSTREAM PROCESSING Extracellular enzymes Centrifuge – removes cells Concentrate – removes water Purify – removes impurities

Intracellular enzymes Filter – separate cells Centrifuge – concentrate cell mass Drying – provides cells for packaging