Since enzymes are so specific, powerful – many thousands of times faster than some chemical catalysts – and operate at much lower temperatures, too, they are employed in many industries including food and cleaning.
These industries work with tremendous amounts of product, so the amount of enzyme used for each reaction would be equally huge and very uneconomical, as enzymes can be expensive to make. Imagine adding a lot of precious enzymes to a giant processor of, say, baby food or detergent. You’d like to reuse the expensive enzymes, but you can’t extract the enzyme back from the giant processor full of stuff.
This is why enzymes are immobilised onto a surface or tool which is used for processing the product instead. This makes it easy to reuse the enzymes, and improves the stability of their reactions. How may the enzymes be immobilised?
They can be fancily bound chemically to smaller attachment chemicals (small blue spheres) inside nano-sized silica pores, or more conventionally stuck inside semi-permeable jelly balls of calcium alginate.
Alternatively, they can also be immobilised to membranes, for example in filtering fruit juices. Pectinase is used in this process to break down pectin, a polysaccharide found in plant cell walls. This makes juice clear.
All these different immobilisation techniques ensure that the enzymes are easy to manipulate, rescue for reuse and maintain in prime condition to maximise their working life. If they were merely to be thrown into all these wild mixes of fruit juice, detergent, baby food and whatnot, they could hardly be rescued back at all.
Some other examples of enzymes used in industry are lipases which break down fats, for example in detergents; proteinases that break down protein, for example to pre-digest baby food; and isomerases that convert glucose to fructose, for example to add less sugar to dieting foods, as fructose tastes sweeter than glucose.
Immobilised enzymes are also central to various diagnostic reagent strip applications such as blood glucose monitoring and pregnancy testing.
In glucose testing strips, the enzyme glucose oxidase is used to catalyse the first reaction of glucose. Further reactions of its byproducts can be used to create a colour change.