Enzymes at Work

Enzymes are proteins that speed up chemical reactions. Every living cell depends on them, and people have learned to put them to work in kitchens, laundries, paper mills and fields.

Lock and key, roughly

Each enzyme has a pocket, called the active site, shaped to hold a particular molecule. When the right molecule fits, the enzyme helps break it apart or join it to something else, then lets go and repeats the job. Enzymes are not used up, but heat, strong acid and some chemicals can change their shape and stop them working.

Enzymes you meet every week

Enzyme	What it acts on	Where it is used
Amylase	Starch	Baking, brewing, syrups, removing starchy stains
Protease	Proteins	Biological washing powders, tenderising, cheese ripening
Lipase	Fats and oils	Laundry detergents, flavour development in some cheeses
Chymosin	Milk protein (casein)	Cheese making
Pectinase	Pectin in fruit	Clearer fruit juices, more juice from pressed fruit
Lactase	Milk sugar (lactose)	Lactose-free milk products
Cellulase	Plant fibre	Textile finishing, paper processing, research into plant-based fuels

The cheese story

For centuries cheese makers used rennet taken from the stomachs of young calves. The working part of rennet is the enzyme chymosin. Since the early 1990s, much of the world’s chymosin has been made instead by microbes that carry the instructions for it, a process often called fermentation-produced chymosin. It was one of the first food ingredients made this way.

Why washing at lower temperatures works

Biological detergents contain enzymes that break down protein, starch and fat stains. Because enzymes do the chemical work, clothes can often be washed cooler than they once were, which saves energy. Detergent makers keep developing enzymes that hold their shape in cold water.

How industrial enzymes are made

1. A suitable microbe, often a fungus or bacterium, is chosen because it produces the enzyme well.
2. It is grown in large fermenters with food, air and a controlled temperature.
3. The enzyme is separated from the microbes, purified and checked.
4. It is formulated as a liquid or granule for its job.

Next guide: Plant Biotech