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Ligand Binding Affinity

Meaning

Ligand binding affinity is a quantitative measure of the strength and duration of the non-covalent molecular attraction between a specific ligand, such as a hormone or neurotransmitter, and its corresponding receptor protein. High affinity indicates that a lower concentration of the ligand is required to occupy a significant proportion of the available receptors and elicit a biological response. This crucial pharmacological parameter is typically expressed as the dissociation constant ($text{K}_d$), which dictates the sensitivity of a target cell or tissue to a circulating signaling molecule. Understanding affinity is essential for designing effective hormone therapies and pharmacological agents.