At a pH of 8.6, proteins are charged in which way?

At a pH of 8.6, many proteins tend to carry a negative charge. This is because the isoelectric point (pI) of a protein is the pH at which the protein has no net charge. If the pH is above the pI, the protein will typically lose protons from its acidic side chains, resulting in a net negative charge.

For proteins, which are made up of various amino acids, the ionizable groups (both acidic and basic) will interact with the surrounding pH level. At a basic pH such as 8.6, the environment is more likely to deprotonate carboxylic acid side chains, which are prevalent in many amino acids, thereby causing the protein to have a net negative charge.

In contrast, if the pH were to drop below the pI of the protein, there would be a higher likelihood of the protein acquiring a positive charge due to the protonation of amino groups. Therefore, at a pH of 8.6, proteins generally exhibit a predominant negative charge due to the loss of protons from their ionizable acidic residues.