Enzymes
Proteins that speed up chemical reactions in living things, each acting on particular molecules without being used up.
Enzymes are proteins that act as catalysts: they speed up particular chemical reactions in cells, often millions of times, and come out unchanged at the end. Each enzyme has an active site shaped to fit certain molecules, which is why enzymes are so specific.
Everyday examples are everywhere. Amylase in saliva starts breaking starch into sugar while you chew bread. In curing vanilla, the pod's own enzyme β-glucosidase cuts a sugar off glucovanillin, releasing free vanillin, the main aroma molecule. A green pod hardly smells, while a cured bean holds about 1-2% vanillin by weight.
Temperature matters. Most enzymes work faster as they warm up, until heat changes their shape and they stop working. That is why vanilla pods are scalded only briefly, at around 63 °C, and then kept warm at 45-50 °C to sweat for a few days.
A common misconception is that enzymes are alive. They are not: they are molecules, and they can work in a test tube or a washing-powder box long after the cell that made them has gone.
See it in action
Coming up in future stories
- A Yellowstone Hot Spring Gave Us PCR 1966–1983 · Mushroom Spring, Yellowstone, and Cetus, California
- Bacteria Found Eating Bottles in a Japanese Dump 2016 · a PET bottle recycling site, Sakai, Japan
- Brazil's Soya Grows on Bacteria, Not Fertiliser 1950s–1990s · Rio de Janeiro, Brazil
- Gamers Solved a Virus Protein That Stumped Scientists 2011 · University of Washington, Seattle (players worldwide)
- He Drank the Bacteria to Win the Argument 1984 · Perth, Australia
- Jamaica's National Fruit Is Poisonous Until It Opens 1950s–60s · Mona, Jamaica (and Muzaffarpur, India, 2014)
- Ketchup Was Once a Fermented Fish Sauce 17th century · southern China and Southeast Asia → Britain
- The Man With a Window Into His Stomach 1822 · Mackinac Island, Michigan