How to calculate Isoelectric point of Amino Acids

The isoelectric point is defined as the pH at which no net migration takes place in an electric field, while the isoionic point is defined as the pH at which there is no net charge on the molecule. In a deionized solution, the isoelectric and isoionic points are for most purposes identical. The isoelectric point of gelatine is dependent on the type of pretreatment applied during manufacture. Type A or acid-processed gelatins have isoelectric points that can vary from 6.5 to 9.0. Acid ossein gelatins are at the lower end of the range with isoelectric point values of 6.5–7.5, while acid pigskin is more likely to have values from 7.5 to 9.0. Many physical properties of gelatine have either a minimum or a maximum at the isoelectric point. This means that acid- and alkali-derived gelatines can sometimes perform quite differently in the same system. Keywords: Which of these amino acids has a side chain that can become ionized in cells? A) Histidine B) Leucine C) Proline D) Threonine In lysine, the pKa of the side chain is about 10.5. Assuming that the pKa of the carboxyl and amino groups are 2 and 9, respectively, the pI of lysine is closest to: A) 5.5 B) 6.2 C) 7.4 D) 9.8 #aminoAcids #isoelectricPoint #polypeptide #peptide #protein