Antibodies Know Right From Left

Knowing right from left is essential in many areas of life - even on the molecular level. Prof. Meir Wilchek of the Weizmann Institute's Biological Chemistry Department, working with an international team of researchers, has now discovered that this ability is particularly prominent in antibodies, the Y-shaped proteins produced by the immune system.

Antibodies fight disease-causing intruders, such as viruses, by binding with the intruders' molecules and thus neutralizing them. In a study reported in the April 8 issue of the Journal of the American Chemical Society, the scientists found that in seeking out appropriate molecules with which to bind, the antibodies distinguish between left- and right-handed amino acids, the building blocks of proteins. Thus, some antibodies only bind with left-handed amino acids, completely ignoring the right-handed ones, while others only bind with right-handed amino acids.

The antibodies are so exquisitely precise they can recognize a small part of a single amino acid, known as the chiral center, which determines the amino acid's orientation to the right or left. Molecules that are identical in chemical composition but whose structures are mirror images of one another, like the right and left hand, are called chiral (from chir, Ancient Greek for "hand"). Such molecules have different properties and are not superimposable. This research may prove of great significance for the pharmaceutical industry. It has been shown in the past few years that in many drugs it is only the compound of a particular "handedness" that is effective, while its "mirror image" is useless or even harmful. Therefore, developing an efficient way to identify and sort out left- and right-handed molecules with the help of antibodies could pave the way for more effective pharmaceuticals.