Hochaffinität

Hochaffinität refers to the high affinity of a substance, typically a ligand or enzyme substrate, for its binding partner, such as a receptor, enzyme, or antibody. The term originates from the German language, where *hoch* means "high" and *Affinität* translates to "affinity." In biochemistry and pharmacology, it describes the strength of a non-covalent interaction between two molecules, often measured by the dissociation constant (Kd), where a lower Kd indicates a higher affinity.

In enzyme kinetics, a substrate with high affinity binds tightly to the enzyme’s active site, facilitating efficient catalysis. This is particularly important in drug design, where high-affinity ligands can selectively target specific biological receptors, minimizing off-target effects. For example, monoclonal antibodies often exhibit high affinity for their antigens, enabling precise therapeutic interventions.

The concept is also relevant in molecular biology, where DNA-binding proteins or transcription factors demonstrate high affinity for specific DNA sequences, regulating gene expression. Techniques such as surface plasmon resonance (SPR) or isothermal titration calorimetry (ITC) are commonly used to quantify Hochaffinität experimentally.

While high affinity is desirable in many applications, it can also lead to unintended consequences, such as prolonged drug-receptor interactions or irreversible binding in certain cases. Balancing affinity with other properties, like selectivity and kinetic stability, is crucial in optimizing molecular interactions for practical use.