In a folded globular protein the side chains of a Lys and an Asp come into close

Question

In a folded globular protein the side chains of a Lys and an Asp come into close enough proximity to interact. What is the strongest type of noncovalent interaction would be expected between these two amino acid side chains in the physiological pH range? a) Hydrophobic b) metal ion coordination c) ionic interaction (salt bridging) d) hydrophilic interactions e) hydrogen bond f) disulfide bond A newly sequenced protein has been crystallized and analyzed by X-ray crystallographic methods. It consists of 200 amino acids linked by peptide bonds in a single polypeptide chain. One region of the protein has multiple alpha helical structures and is the catalytic site for the protein. Another region has a barrel composed of multiple antiparallel beta sheets where the redox cofactor binds. Which of the following would be expected to be part of this protein?. a) primary structure b) secondary structure c) tertiary structure d) quaternary structure e) motifs f) domains Answer each of the following as directed by the question. In the ____ allosteric model an equilibrium occurs between low affinity and high affinity forms of the protein, with changes occurring independently in individual subunits with changes ligand concentration. What are two examples of diseases that have been determined to be caused by or have misfolded proteins as a consequence of the disease?

Explanation / Answer

The interaction is ionic interaction (salt bridging).

Salt bridges are ionic bonds between ionized R groups of basic and acidic amino acids. In folded globular protein side chain at physiological pH negatively-charged carboxyl groups on aspartic acid (Asp) attracted by the positively-charged free amino groups on lysine (Lys). This is a ionic bond where R groups are carboxylate(coo-) and amino group (NH3+)

( For LYSINE amino acid, the protonated form predominate at physiological pH and for aspartic acid -the deprotonated forms predominate at physiological pH),

Disulfide bond, also called an S-S bond, or disulfide bridge, is a covalent bond -type of interaction .

There is no metal involved in such interactions for these amino acid.

Hydrophilic interactions are attractions between the external aqueous environment and the R groups of polar amino acids. There is no such kind of environment for these amino acids here.

Hydrogen bond is between hydrogen atom and electronegative atom of N. At physiological pH, amino acids are in ionic form so such interaction not possible.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

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