What is the Origin of Ligand Binding Capacity?

This is a core concept in biochemistry and receptor pharmacology, derived from the principles of mass action and equilibrium binding studies. The term is essential for understanding the bioavailability and free concentration of circulating hormones, which is the biologically active fraction. Clinical measurements of binding capacity help to interpret total hormone levels accurately.

What is the Mechanism of Ligand Binding Capacity?

Ligand binding capacity is directly proportional to the concentration of the binding protein and its affinity for the ligand. When the total concentration of the binding protein is high, a greater fraction of the total hormone is sequestered and biologically inactive, thereby lowering the free hormone level. The physiological function of this capacity is to buffer rapid changes in hormone concentration, protect hormones from degradation, and facilitate their uniform distribution throughout the body.

Ligand Binding Capacity ∞ Area

Ligand Binding Capacity

Meaning

The maximal quantity of a specific signaling molecule, or ligand, that can be reversibly bound by a receptor or carrier protein within a given biological system, such as plasma or a cell membrane. This capacity is a critical measure of the total number of available binding sites and the concentration of the carrier protein itself. In the context of hormonal health, it often refers to the capacity of plasma proteins like Sex Hormone-Binding Globulin (SHBG) or Corticosteroid-Binding Globulin (CBG) to bind their respective steroid hormones.