Chapter 3: Exercise #2 Given the pK of each of the following groups, fill in the

Question

Chapter 3: Exercise #2 Given the pK of each of the following groups, fill in the rest of the table using negative charge, positive charge, or uncharged for status. For form use COOH, COO, etc. physiological pH Chemical Group Status Form 3.0-3.2 11.6-12.6 9.8-10.4 4.5 3.0-4.7 9.1-10.8 5.6-7.0 9.4- 10.6 7.8-8.4 C-terminal carboxyl Arginine guanidyl Tyrosine hydroxyl Glutamate side-chain carboxyl Aspartate side-chain carboxyl Cysteine sulfhydryl Histidine imidazole Lysine side-chain amino N-terminal amino Is the tetranentide Ala-Glu-Gly-Lys a good buffer at pH 7.02

Explanation / Answer

The physiological pH of our body is approximately 7.4

Now if the pK of a molecule is less than the given pH (7.4) then the compound will be deprotonated meaning the H+ ion will be removed. This happens as less number of Hydrogen ions are present.

If the pK of a molecule is more than the given pH then the compound will be protonated meaning an H+ ion will be added to the molecule.  This happens as less number of Hydrogen ions are present.

Chemical Group Comparison Status Form

C terminal carboxyl pK < pH Negative charge COO-

Arginine guanidyl pK > pH Postive charge NH3+

Tyrosine hydroxyl     pK > pH Postive charge NH3+

Glutamate side-chain carboxyl   pK < pH Negative charge COO-

Aspartate side-chain carboxyl pK < pH Negative charge COO-

Cysteine sulfhydryl   pK > pH Postive charge NH3+

Histidine imidazole   pK < pH Negative charge COO-

Lysine side-chain amino pK > pH Postive charge NH3+

N-terminal amino pK > pH Postive charge NH3+

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.