Question

• What determines protein structure?
• Describe the experiment that lead to this conclusion?
• What type of chemical interactions are involved in the tertiary protein structure?

Answer 1

Ans) Amino acid sequence determines protein structure and its native confirmation.

Ans) The experiment that led to this conclusion was carried out by Christian Anfinsen and colleagues in early 1960s. Anfinsen studied the refolding of protein ribonuclease A. Ribonuclease A is an enzyme that contains 124 amino acid residues and 4 disulfide linkages.

In the presence of urea, a denaturant, and beta- mercaptoethanol, a reducing agent, ribonuclease is denatured and the disulfide bonds are broken. When the protein is allowed to renature by removing the denaturant and the reductant, the protein regains its native confirmation, including four correctly paired disulfide bonds.

This finding provided the first evidence that the amino acid sequence of a polypeptide chain contains all the information required to fold the chain into native three dimensional structure.

Ans) Types of chemical interactions are involved in the tertiary protein structure are:

Tertiary structure involves both covalent and non covalent interactions.

Covalent bonds- The most prominent covalent bonds in tertiary structure are the disulfide bridges.

Non-covalent interactions are:

• Hydrophobic interactions
• Van Der Waals interactions
• Electrostatic interactions
• Hydrogen bonds

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