Digestive enzymes can be useful
We make proteins by breaking down the ones we eat, then building new ones from their component amino acids. This breaking down is digestion, and lots of enzymes contribute. Proteases, for instance, hydrolyse (break) the peptide bonds in protein.
Some proteases are very specific and do more than food digestion. Several viruses, including HIV and poliovirus, use some of their proteases to produce finished protein products from larger precursor polypeptides. Insulin is produced in the same way (read our article ‘Focus Protein: Insulin’).
Digestive enzymes are useful in industry. Researchers have discovered enzymes in bacteria that can digest wood to produce liquid biofuel. Biofuels are fuels made from living matter, such as trees or cereal crops. At its most efficient, biofuel is carbon neutral because the carbon dioxide released when the fuel burns was absorbed from the atmosphere relatively recently, during the life of the plant.
In theory, using the woody parts of plants and crop waste would enable biofuel to be produced without competing with food production – and reduce carbon dioxide emissions by being used in place of fossil fuels. However, the potential impact on forests of large-scale biofuel production remains to be seen.
Questions for discussion
- Describe three other ways that enzymes are used in industrial settings.
- How should we decide how much land to use for biofuels and how much to use for food production?