[Biochemistry 1] amphoteric properties of proteins

The amphoteric properties of protein

1. Amphoteric Properties of Proteins Group 3 Agus Arianto (F02111013) Atikah (F02111045) Desy Indra Wahyuni (F02111033) Nur Desi Yani (F02111007)

2. Acid-Base P roperties of A mino A cids All amino acids contain at least two ionizabl e groups the α -amino group and the α -carboxylic group, some contain an additional acidic or basic group in their side chain,which are responsible for the amino acids, acid-base behaviour . As a result of their ionizability the following equilibrium reaction can be written : R-COOH R-COO - + H + R-NH 2 R-NH 3 + Since these reactions are reversible this indicates that they can act as acids or as bases.

3. Amphoteric Properties of Amino Acids A mino acids due to the presence of their ionizable α -amino and α -carboxylic group can act sometimes as acids and sometimes as bases depending on the pH of their media.

4. Zwitterions In chemistry, a  zwitterion   (formerly called a  dipolar ion ) is a neutral molecule with a positive and a negative electrical charge. Unlike simple amphoteric compounds that might only form  either  a cationic or anionic species depending on external conditions, a zwitterion simultaneously has both ionic states in the same molecule .