Kinetic asymmetry could revolutionize science and solve the mystery of life

Gravitational and electromagnetic forces are called mutual forces when two objects attract or repel each other. But interactions in the natural world are not subject to the law of reciprocity. For example, a predator is attracted to its prey, but the prey tends to flee from it. Such behaviors are essential for the complex behaviors of organisms. In the case of microscopic systems (such as bacteria), the mechanism of non-reciprocal interactions has been explained using hydrodynamic or other external forces. It was also thought that similar types of forces could explain interactions between single molecules.

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A team of scientists from the University of Maine Describe a mechanism by which single molecules can interact non-reciprocally, without hydrodynamic effects. It produces local gradients of reactants and products as a result of reactions facilitated by any chemical catalyst of which an enzyme is a biological example. Because the response of a catalyst to a gradient depends on its properties, it is possible for one molecule to be repelled by another molecule but attracted to another molecule. Details are described in the magazine Chemistry.

Kinetic asymmetry is the key to nonreciprocal interactions

What controls the direction of the reaction along the concentration gradient is what is called kinetic asymmetry. It is a property of the enzyme itself and may be subject to evolution and adaptation. Nonreciprocal interactions enabled by kinetic asymmetry allow molecules to interact with each other and may have been crucial in the processes by which simple matter becomes complex.

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This research has contributed to the development of a field called active substances. In previous work, non-reciprocal interactions were introduced by integrating custom forces, but the research of Prof. Ayusman Sen and Dr. Niladri Sekhar Mandala describe the basic molecular mechanism by which such interactions between individual molecules can occur. This research builds on previous work in which the same authors showed how a single catalytic molecule can use energy from the reaction it catalyzed to perform directional movement across a concentration gradient.

We are at the beginning of this work, but I see understanding kinetic asymmetry as a potential opportunity to understand the evolution of life from simple molecules. Not only does it provide insight into the complexity of matter, but it can also enable the design of molecular machines and related technologies.
Professor R. Dean Astomian of the University of Maine

The kinetic asymmetry that occurs in determining interactions between different catalysts is important for the directionality of biomolecular machines and has been taken into account in the design of artificial actuators. Scientists are trying to understand the organizing principles behind the various catalysts that may have created the earliest metabolic structures that ultimately led to the evolution of life.