isoelètric

Isoelectric refers to a state or condition where a molecule or substance has no net electrical charge. This point is particularly relevant in the study of proteins and amino acids, which are zwitterionic, meaning they possess both positive and negative charges within the same molecule. The isoelectric point (pI) is the specific pH value at which the net charge of a molecule is zero. At this pH, the number of positive charges equals the number of negative charges.

Understanding the isoelectric point is crucial in various biochemical and chemical processes. For instance, in chromatography, the pI of a protein determines its behavior when subjected to different pH conditions and electrical fields. At its isoelectric point, a protein will exhibit minimal solubility, as the lack of net charge reduces electrostatic repulsion between molecules, causing them to aggregate. This property is exploited in protein precipitation techniques for purification and separation.

Furthermore, the isoelectric point influences the biological activity and function of many biomolecules. Enzymes, for example, often have an optimal pH range for their activity, and this range can be closely related to their pI. Changes in pH away from the isoelectric point can alter the ionization state of amino acid residues within the protein, potentially affecting its three-dimensional structure and its ability to bind to substrates or perform its catalytic function. The concept of isoelectricity is fundamental to understanding molecular behavior in aqueous solutions and is applied in fields ranging from molecular biology and biochemistry to industrial processes like food production and waste treatment.