An amino acid is usually more soluble in aqueous solvent at pH extremes than it

Question

An amino acid is usually more soluble in aqueous solvent at pH extremes than it is at a pH near the isolelectric point of the amino acid. (Note that this does not mean that the amino acid is insoluble at a pH near its pI.)

Which of the following statements correctly explains this phenomenon?

(Select all that apply.)

At pH extremes, the amino acid molecules mostly carry a net charge, thus increasing their solubility in polar solvent.

At very low or very high pH, the amino acid molecules have increased charge, thus form more salt bonds with water solvent molecules.

At pH values far from the isoelectric point, individual amino acid molecules have greater kinetic energy, thus more readily stay in solution.

The neutral charge of an amino acid molecule at its isoelectric point will make the molecule hydrophobic.

Explanation / Answer

At isoelectric point the amino acid is neutral that is it does not have any charge.

At low pH ,the amino acid has net positive charge as both carboxylic acid and amine group is protonated.

At high pH ,the amino acid has net negative charge as carboxylic acid is deprotonated and amine group is neutral.

Due to the charge possessed by amino acid at low or high pH ,they are easily soluble by polar protic solvent as more salt bonds will be formed with water molecules (H+ and OH-) while in case of isoelectric point due to neutral charge the amino acid is soluble but very slightly .

option1 and option 2 are only correct.

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