By means of scanning tunnelling microscopy movies and theoretical simulations they have shown how dynamic interactions induce the molecular fit needed for the transfer of structural information to higher levels of complexity. This dynamic picture illustrates how recognition works at the very first steps, tracking back the path in the evolution of complex matter. (
Angewandte Chemie International April 20th 2007)
If one thinks that there are thousands of times more molecules forming our body than stars in the universe it is astonishing how all these molecules can work together in such an organised and efficient way. How can our muscles contract to make us walk? How can food be metabolised every day? How can we use specific drugs to relieve pain?
To work as a perfect machine, our body ultimately relies on the capability of each little part (molecule) to know a specific function and location out of countless possibilities. To do this, molecules carry information in different ways. An international team at the Max Planck Institute for Solid State Research in Stuttgart, in collaboration with scientists from the Fraunhofer Institute in Freiburg and the King's College London are seeking to find out how the information can be passed on at the very first steps: from the single molecule level to structures of increasing complexity and functionality.
The key to understanding all biological processes is recognition. Each molecule has a unique composition and shape that allows it to interact with other molecules. The interactions between molecules let us - as well as bacteria, animals, plants and other living systems - move, sense, reproduce and accomplish the processes that keep all living creatures alive.
A very common example of recognition can be experienced in daily life whenever one meets someone and shakes right hands. In principle, one can also shake left hands; the fact that we do it with the right has historically been a sign of peace, used to show that both people hold no weapon. But, have you ever attempt to shake the right hand of a person using your left hand? No matter how the two hands are oriented, you will never fit your left hand with the right hand of your friend.
Many molecules can recognise each other and transfer information exactly in the same way, they can either be "right handed" (D) or "left handed" (L). This property called "chirality" is a spectacular way to store information: a chiral molecule can recognise molecules that have the same chirality (same "handedness", L to L or D to D) and discriminate the ones of different chirality (L to D and D to L).
Probably one of the most exciting mysteries of Nature is why the building blocks of life, i.e. amino acids (the building blocks of proteins) are exclusively present in the chiral L form and sugars (which constitute DNA) are all in the D form. Once more, the reason for this preference is "historical", but this time goes back millions of years till the origins of the biological world. Scientists believe that current life forms could not exist without the uniform chirality ("homochirality") of these blocks, because biological processes need the efficiency in recognition achieved with homochiral substances. In other words, the separation of molecules by chirality was the crucial process during the Archean Era when life first emerged.
Researchers of the Max Planck Institute for Solid State Research have now used the "nanoscopic eye" of a scanning tunnelling microscope to make movies following how two adsorbed molecules (diphenylalanine, the core recognition motif of Alzheimer amyloid polypeptide) of the same chirality can form structures (pairs, chains) while molecules of different chirality discriminate and cannot form stable structures.
As it occurs when you shake the hand of your friend, the fact that the two homochiral hands are complementary by shape is not enough, you both have to dynamically adapt and adjust your hands to reach a better fit, a comfortable situation. By a combination with theoretical simulations done at Kings College London, the researchers have shown for the first time this dynamic mechanism of how two molecules "shake hands" and recognise each other by mutually induced conformational changes at the single molecule level.
We live in houses, wear clothes and read books made of chiral cellulose. Most of the molecules that mediate the processes of life like hormones, antibodies and receptors are chiral. Fifty of the top hundred best-selling drugs worldwide are chiral. With this contribution to the basic mechanism of chiral recognition, the researchers have not only tracked back to the very first steps in the evolution of living matter but have also shed light on our understanding and control of synthetic (man-made) materials of increasing complexity.
Related link: Molecular handshake (film) --
http://www.fkf.mpg.de/kern/videos/videoV1.mpg
Source: Max-Planck-Gesellschaft
Related stories:
Scientists watch on the atomic level how individual molecules recognize each other
The body is an almost perfect machine. For it to function properly, each individual component, that is each molecule, must reliably fulfill its specific function. Each molecule must thus “recognize” other molecules and work with them. A team of researchers from the Max Planck Institute for Solid State Research in Stuttgart, the Fraunhofer Institute in Freiburg, and King’s College in London, has now successfully filmed pairs of molecules during the recognition process. As reported to the journal
Angewandte Chemie, the shapes of the molecules change to accommodate each other.
To catch an intermediate
A new technique for capturing the short-lived but critical "intermediate" compounds that help carry chemical reactions which take place in aqueous solution from their starting point to the final product has been developed by researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab). This technique basically entails temporarily trapping the elusive transients inside molecular pyramids.
Innate immune system targets asthma-linked fungus for destruction
A new study shows that the innate immune system of humans is capable of killing a fungus linked to airway inflammation, chronic rhinosinusitis and bronchial asthma. Researchers at Mayo Clinic and the Virginia Bioinformatics Institute (VBI) have revealed that eosinophils, a particular type of white blood cell, exert a strong immune response against the environmental fungus
Alternaria alternata. The groundbreaking findings, which shed light on some of the early events involved in the recognition of
A. alternata by the human immune system, were published recently in the
Journal of Immunology.
Fingerprints provide clues to more than just identity
Fingerprints can reveal critical evidence, as well as an identity, with the use of a new technology developed at Purdue University that detects trace amounts of explosives, drugs or other materials left behind in the prints.
Researchers discover how antidepressants and cocaine interact with brain cell targets
In a first, scientists from Weill Cornell Medical College and Columbia University Medical Center have described the specifics of how brain cells process antidepressant drugs, cocaine and amphetamines. These novel findings could prove useful in the development of more targeted medication therapies for a host of psychiatric diseases, most notably in the area of addiction.
Improving computer memory, solar cells goal of UH chemist
A high-tech breakthrough in solar cells and flash drives may just come down to good old-fashioned pencil and paper calculations, says an award-winning young chemist at the University of Houston.
Unique pheromone detection system uncovered
Researchers at UT Southwestern Medical Center have overturned the current theory of how a pheromone works at the molecular level to trigger behavior in fruit flies.
Immune molecule that plays a powerful role in avoiding organ rejection identified
When a mouse's immune system is deciding whether to reject a skin graft, one powerful member of a molecular family designed to provoke such a response can effectively reduce the visibility of the mouse's own cells and help the graft survive, researchers say.
