Histidine–histidine hydrochloride buffering system

The **histidine–histidine hydrochloride buffering system** is a non-enzymatic, amino acid-based buffer frequently used in biochemistry, cell culture, and protein formulation to maintain stable pH, typically in the range of 5.0 to 8.0. Its buffering capacity arises from the imidazole side chain of histidine, which has a pKa near physiological pH and can reversibly accept or donate protons, making it suitable for modulating environments relevant to protein function and stability[3][5]. It is not a molecular target in the sense of a receptor, enzyme, transporter, or conventional drug interaction partner, but rather a chemical system for experimental and therapeutic formulation. Histidine-containing buffers are particularly valued for minimizing protein aggregation and maintaining activity during bioprocessing and storage, though temperature or formulation-related risks such as pH drift and aggregation may exist[4]. **Note:** This entry represents a *buffering system* and not a biological macromolecule (receptor, enzyme, etc.), and thus is not considered a traditional therapeutic target. The query should likely be mapped to "null" for canonical molecule entries.

Other names

Histidine bufferHistidine–HCl bufferL-histidine bufferHistidine hydrochloride buffer

Proton donor and acceptor; maintains extracellular and intracellular pH in experimental conditions