Which of these amino acids will migrate slowest to the anode end at the physiological pH-?
Positively charged (cationic) amino acids are attracted to the negative electrode (the cathode), and negatively charged (anionic) amino acids are attracted to the positive electrode (the anode). An amino acid at its isoelectric point has no net charge, so it does not move. So at the physiological pH, amino acid with positive charge will move slowest towards the anode (positively charged electrode). Thus lysine will migrate slowest to the anode end. Electrophoresis uses differences in isoelectric points to separate mixtures of amino acids. A streak of the amino acid mixture is placed in the center of a layer of acrylamide gel or a piece of filter paper wet with a buffer solution. Two electrodes are placed in contact with the edges of the gel or paper, and a potential of several thousand volts is applied across the electrodes. Positively charged (cationic) amino acids are attracted to the negative electrode (the cathode), and negatively charged (anionic) amino acids are attracted to the positive electrode (the anode). An amino acid at its isoelectric point has no net charge, so it does not move. Amino acid classification:- Acidic Amino acids: These amino acids have two - COOH groups and one -Nil, group. At neutral pH their side chains are fully ionized containing a negatively charged carboxylate group (-COO). Eg. Aspaic acid (Aspaate) & Glutamic acid (Glutamate) Basic Amino Acids: They have one -COOH group and two -NH, groups. At neutral pH. their side chains are fully ionized and positively charged. Eg. Arginine, Lysine, Histidine Rest all amino acids are neutral amino acids. Ref: Test book of Biochemistry, By Chatterjee Shinde, 4th Edition, Page 59
Aspaic acid
Glycine
Valine
Lysine