Question

For the following questions, consider six proteins, each 50 amino acids long, made of just a single type of amino acid. Protein P is made of proline; K, lysine; S, serine; E. glutamic acid; F, phenylalanine.; and G. glycine. Your answers are going to be P, K, S, E, F or G.

1. Which of these proteins would move fastest on SDS-PAGE?

2. Which of these proteins would move fastest on Sephadex?

3. Which of these proteins would move closest to the anode in isoelectric focussing?

4. Which of these proteins would stick best to CM-cellulose?

5. Which of these proteins would not stick to DEAE-Sephadex well?

ation BUT these points are not enough Something is missing rom enzyme-catalyzed reaction? (10) Quiz 6.06/10/19 For the following questions, consider six proteins, each 50 amino acids long, made of just a single type of amino acid. Protein P is made of phenylalanine proline; K, lysine; S, serine; E, glutamic acid, SDs-PAGE d G, glycine Your answers are going to be P, K, S, E, F or G. and i) Which of these proteins would move i) Which of these proteins would move t on Sephadex? iii) Which of these proteins would move closest to the anode in isoelectric focussing? iv) Which of these proteins would stick best to CM-cellulose? v) Which of these proteins would not stick to DEAE-Sephadex well? DEA-S protoin speed

Answer 1

(i) Since, Glycine (G) has the lowest weight (75 Da) among all other amino acids;
[ P - 115 Da , K- 146 Da, S - 105 Da, E - 147 Da, F - 165 Da], it will move the fastest in SDS PAGE.

(ii) G will move the fastest in Sephadex. (Same reason as (i) )

(iii)  In proteins, the isoelectric point (pI) is defined as the pH at which a protein has no net charge. When the pH is greater than pI, a protein has a net negative charge and moves towards anode whereas when the pH is less than pI, a protein has a net positive charge and moves towards cathode.

Therefore, K will move closest to the anode.

(iv) Since, CM-cellulose is negatively charged, positively charged protein (E) will stick on it well.