5. (20p) A number of natural proteins are very rich in disulfide bonds, and thei

Question

5. (20p) A number of natural proteins are very rich in disulfide bonds, and their mechanical properties (tensile strength, viscosity, hardness, etc) are correlated with the degree of disulfide bonding. For example glutenin, a wheat protein rich in disulfide bonds, is responsible for the cohesive and elastic character of dough made from wheat flour. Similarly, the hard, tough nature of tortoise shell is due to the extensive disulfide bonding in its -cheratin, a) what is the molecular basis for the correlation between disulfide-bond content b) most proteins are denatured and lose their activity when briefly heated to 65 be heated longer at higher temperatures to denature them. One such protein is single chain and contains 3 disulfide bonds. On cooling a solution of denatured and mechanical properties of the protein? 0C. However, globular proteins that contain multiple disulfide bonds often must bovine pancreatic trypsin inhibitor (BPTI), which has 58 amino acid residues in a BPTI, the activity of the protein is restored. What is the molecular basis for this property?

Explanation / Answer

Disulfide bonds are covalnt bonds, so they are stronger than non covalent inetractions like hydrogen bonds, hydrophobic interactions, van der Waals interactions etc, that stabilize three dimensional structure of most proteins.
Disulphide bond occurs between same domain or different domain of the protein by cross linking disulphide bond that increasing stifness, hardness and mechanical strength.

If temperature increased that increases the thermal motion of polypeptide chains and vibrational motion of hydrogen bonds leads to thermal denaturation or unfolding of proteins. Cystine residues (disulfide bonds) can, depending on their location in the protein structure, prevent or restrict the movement of folded protein
domains, block access of solvent water to the interior of the protein, and prevent the complete unfolding of the protein. Refolding to the native structure from a random conformation is seldom spontaneous, owing to the very large number of conformations possible. Disulfide bonds limit the number of conformations by allowing only a few
minimally unfolded structures, and hence the protein returns to its native conformation more easily upon cooling.

Related Questions

Navigate

• Browse (All)
• Browse 5
• Subjects

---

---

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