Life is left

2001/02/16 Galarraga Aiestaran, Ana - Elhuyar Zientzia

• Biologia

One of the mysteries of biology is related to mirrors. Because many biological molecules formed by equal atoms are figures of mirrors, like hands. They have the same atoms but they are not the same and their properties are also different. The proteins of all living beings, including bacteria and humans, are made of "left" amino acids, while DNA propellers are "right". But why?

According to a recent study, oneness is related to the origin of these molecules. As published in the journal Nature, it is the result of the strategy they devised to survive in the original soup in which they were born. Only the molecules capable of multiplying managed to advance and until today have repeated the same model.

The molecules that form synthetic organic materials are formed by the left half (L-enantiomero) and the other half by the right (D-enantiomero), that is, although they have the same shape, the configuration they acquire in the space is as if reflection of the other. Life, however, is made of L-amino acids and by this characteristic is said to be homociral.

Researchers have used peptides, i.e. parts of proteins, to find out why the biological world is subject to homocirality, and have shown that the results were chosen by the ability of homocyral molecules to easily multiply.

To demonstrate this, four peptide fragments have been used, each of them composed exclusively of amino acids D or L. Peptides have been mixed and combinations have been analyzed.

The result has been significant, since almost all the products obtained have been homociral. Once constituted, they act as a model accelerating their multiplication process. On the contrary, heterocyratic molecules have not shown this multiplication strategy.

This research suggests that at the beginning of life it was not essential that the matter of types L and D be exaggerated, since homocyral molecules developed an abundant multiplication strategy.

It seems that homocyral peptides with multiplication capacity played a fundamental role in the beginning of life, and that this type of biological molecules have been imposed because this capacity depended on homocity. However, they still do not know why L-amino acids were chosen and not those on the right.