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using the table above. For paper electrophoresis, predict if each of the followi

ID: 979757 • Letter: U

Question

using the table above.

For paper electrophoresis, predict if each of the following amino acids would migrate rapidly towards the cathode (negative pole), remain approximately stationary, or migrate rapidly towards the anode (positive pole) at each of the following pH values: pH 3, 5.5, and 10.

a. Aspartic Acid                      b. Arginine                  c. Threonine

Table 3.2 pKa values of acidic and basic constituents of free amino acids at 25°C Amino acid pKa value Carboxyl Amino Side group group chain 9.8 9.9 9.7 9.7 9.8 Methionine 2.1 9.3 10.6 9.3 Tryptophan 2.5 9.4 9.2 9.1 2.4 2.4 2.3 2.3 2.3 Glycine Alanine Leucine Isoleucine Proline 2.0 Phenylalanine 2.2 Serine Threonine 2.1 Cysteine 1.9 10.7 8.4 Tyrosine 2.2 9.2 10.5 Asparagine 2.1 Glutamine 2.2 Aspartic acid 2.0 9.9 3.9 Glutamic acid 2.1 Lysine Arginine 1.8 Histidine 2.2 3 8.7 9.5 4.1 2.2 9.1 10.5 9.0 12. 9.3 6.0

Explanation / Answer

For paper electrophoresis, the prediction of amino acid movement,

a. aspartic acid

at pH 3.0 : migrate towards cathode

at pH 5.5 : migrate towards anode

at pH 10 : migrate towards anode

b. Arginine

at pH 3.0 : migrate towards cathode

at pH 5.5 : migrate towards cathode

at pH 10 : remain approximately stationary

c. Threonine

at pH 3.0 : migrate towards cathode

at pH 5.5 : migrate towards cathode

at pH 10 : migrate towards anode