Suppose you have solutions of the following amino acids buffered at a pH of 7.0. In which of the solutions would the major species have no net charge?. SELECT ALL THAT APPLYA. Histidine (6.0)B. Glutamic Acid (4.2)C. Cysteine (8.3)D. Isoleucine (>14)E. Lysine (10.0)

The net charge of an amino acid at a given pH depends on the pKa values of its ionizable groups. The pKa value is the pH at which half of the molecules of a substance are deprotonated. If the pH is less than the pKa, the molecule will carry a positive charge. If the pH is greater than the pKa, the molecule will carry a negative charge.

A. Histidine has a pKa of 6.0. At a pH of 7.0, which is greater than the pKa, histidine will be deprotonated and carry a negative charge.

B. Glutamic Acid has a pKa of 4.2. At a pH of 7.0, which is greater than the pKa, glutamic acid will be deprotonated and carry a negative charge.

C. Cysteine has a pKa of 8.3. At a pH of 7.0, which is less than the pKa, cysteine will be protonated and carry a positive charge.

D. Isoleucine has a pKa greater than 14. At a pH of 7.0, which is less than the pKa, isoleucine will be protonated and carry a positive charge.

E. Lysine has a pKa of 10.0. At a pH of 7.0, which is less than the pKa, lysine will be protonated and carry a positive charge.

Therefore, none of the given amino acids would have no net charge at a pH of 7.0.

The net charge of an amino acid at a given pH depends on the pKa of its side chain. If the pH is lower than the pKa, the group will be protonated. If the pH is higher than the pKa, the group will be deprotonated. At a pH equal to the pKa, the group will be half protonated and half deprotonated, resulting in no net charge.

A. Histidine (pKa = 6.0): At pH 7.0, the side chain of histidine will be deprotonated, resulting in a negative charge. Therefore, histidine will not have a net charge of zero at pH 7.0.

B. Glutamic Acid (pKa = 4.2): At pH 7.0, the side chain of glutamic acid will be deprotonated, resulting in a negative charge. Therefore, glutamic acid will not have a net charge of zero at pH 7.0.

C. Cysteine (pKa = 8.3): At pH 7.0, the side chain of cysteine will be protonated, resulting in a positive charge. Therefore, cysteine will not have a net charge of zero at pH 7.0.

D. Isoleucine (pKa > 14): Isoleucine does not have a side chain that can be protonated or deprotonated, so it will always have a net charge of zero, regardless of the pH.

E. Lysine (pKa = 10.0): At pH 7.0, the side chain of lysine will be protonated, resulting in a positive charge. Therefore, lysine will not have a net charge of zero at pH 7.0.

Therefore, the only amino acid that will have a net charge of zero at pH 7.0 is Isoleucine (D).