Biological processes are an ongoing part of everyday life. While processes like breathing and circulation occur on a large enough scale that we can feel their effects, most biological processes occur on a microscopic level. On a molecular basis, binding affinity is a characteristic that is at the root of every process.
What Is Binding Affinity and How Does It Work?
To understand how biological processes work, it is essential to build an understanding of binding affinity. This brief guide will list some important facts about binding affinity crucial to the biological processes we experience every day.
Fact 1: Binding affinity is the relative strength of the interaction that binds a molecule to its unique binding partner.
Biomolecules include proteins, nucleic acids like DNA, carbohydrates, and lipids. They bind with binding partners known as ligands. Binding affinity is measured through a comparison to an equilibrium dissociation constant known as Kd which compares the relative strength of all biomolecular interactions. A lower Kd value indicates a stronger binding affinity, while a higher Kd value represents lower binding affinity.
Fact 2: Biomolecular binding allows the complex formed by the biomolecule and ligand to serve a purpose.
Biomolecular binding does not happen at random. Instead, binding one ligand to another causes the ligand to change the conformation of the target biomolecule, and essentially change its shape and function within the body. Once the biomolecular complex is complete, the ligand can act as an inhibitor, an activator, a signal, a neurotransmitter, or a substrate.
Fact 3: The measure of binding affinity is an essential task for many areas of study.
As mentioned, biomolecules binding to ligands is a process that enables nearly all of our bodily processes to occur. The study of the strength of these bonds is important to many biological sciences. Perhaps, even more importantly, researchers within the drug development field must determine which drugs can bind selectively to certain receptors, and which can do so in a stable manner.
Fact 4: There are numerous ways to measure binding affinity and dissociation constants.
Currently, researchers employ a variety of methods to measure binding affinity and Kd, and all have a particular value, dependent on the type of research and desired outcomes involved. Ligand binding assays typically analyze a sample and the number of biomolecule-ligand complexes formed. Common methods include gel-shift assays, spectroscopic assays, pull-down assays, equilibrium dialysis, and microscale thermophoresis (MST).
Fact 5: Microscale Thermophoresis (MST) allows researchers to measure binding affinity without needing to purify the target protein.
Microscale thermophoresis is a measurement process that utilizes thermophoresis, which moves molecules on a temperature gradient according to changes in molecular properties. Movement is detected and measured using fluorescence and can measure Kd down to one picomolar without requiring purification of the target protein. MST is an essential tool for monitoring binding affinity as well as protein folding.
Ongoing Binding Affinity Studies Propel Drug Research
As drug development proceeds, it is crucial to continue to isolate substances that target biomolecules of interest and ensure each binds in a stable manner. Continued research regarding binding affinity will improve the variety and efficacy of drugs for a large assortment of human ailments. Currently, the future looks bright for the study of binding affinity as it pertains to the drug development sector.
