Jörn Spolander: The chemistry prize winners have recreated life's twisted path choices

The molecules that build up our bodies - and all living things - can chemically form in two different forms. As mirror images of each other (enantiomers). But if you were to mix the various mirror images in a bag and try to put together the genetic material, the proteins, fats and everything else we are made of, it would be a mess. So the chemistry of life produces only one variant. Otherwise we wouldn't exist.

Sometime approximately four billion years ago, when life began to gain momentum on Earth, a chemical path choice was thus made. However, it has proven very difficult to repeat in the laboratory. This year's prize winners are awarded for methods that make it possible to produce only one of the two possible mirror images when producing organic molecules.

Why is this important?

On the one hand, the Nobel laureates' discoveries have provided in-depth knowledge about the origin of life. But above all, it is crucial for producing safe medicines. There are several examples of substances where the two different mirror images can have dramatically different properties. In some cases one enantiomer is ineffective, in others it can be downright harmful.

A well-known example is neurosedyn (thalidomide), a sedative that was also given for nausea in pregnancy. Unfortunately, it turned out that one form of the active molecule causes birth defects and malformations. In that particular case, however, there was no point in purifying the active enantiomer, because it can be converted into its mirror image inside the body.

There are also less dramatic examples. The fragrance carvone can be perceived as either peppermint or cumin, depending on which mirror image of the molecule has been produced.

Are all molecules twisted in the same direction in living things?

The organic molecules that build up the basic components of cells – amino acids, sugar molecules and so on – have the same so-called chirality. It is such a basic part of life that variation does not seem to be favored by evolution. On the other hand, the substances produced by living organisms, for example poisons and fragrances, can occur in different forms that have different properties. The fragrance carvone is one such example.

When did it begin to be understood that organic molecules can occur in different forms?

The French chemist Louis Pasteur discovered in the middle of the 19th century that crystals of tartaric acid affected light rays in a peculiar way. He separated the crystals and discovered that there were two types of crystals, which refracted the light in different directions. When he mixed the crystals, the difference disappeared. It was the starting point into a research area that may seem abstract, but which has provided knowledge about both the function of life and its origin.