Question

In most cases, mutations in the core of a protein that replace a smaller nonpolar side chain in the wild-type (e.g., Ala, Val) with a larger nonpolar side chain (e.g., Leu, Ile, Phe, Trp) in the mutant, result in significant destabilization and misfolding of the mutant. What feature of the protein core explains this observation? Why would such a mutation prevent a protein from folding properly?Interactions of _______side chains in the protein sequence lead to the formation of a tightly packed___________ core. This core is stabilized by a ________number of _________. When a mutation occurs, it destabilizes the protein core and weakens _______ leading to misfolding.a. hydrogen bondsb. polarc. larged. van der Waals contactse. hydrophobicf. disulfide bridgesg. hydrophilich. smalli.nonpolar

Answer 1

Answer:

The correct answers are:

• The protein core is hydrophobic in nature.
• Mutation disrupts the hydrophobic interactions between the non-polar amino acids in the core of the protein thereby destabilising its structure.
• Filling the blanks: non-polar, hydrophobic, large, Van der Waals contacts, Van der Waals contacts.

Explanation:

• The core of a protein is rich in non-polar amino acids like alanine, valine, leucine, etc.
• These amino acids are capable of interacting with each other by the formation of weak Van der Waals contacts with each other.
• Van der Waals forces can be defined as the force of attraction between atoms or molecules when they are in close vicinity with respect to each other.
• The proper folding of a protein requires the proper positioning of each of the side chains of the amino acids in both the interior as well as the exterior of the protein.
• Mutation causing the replacement of a short chain non-polar amino acid with a long-chain non polar amino acid in the protein core requires more space for the long chain non-polar amino acid. This disrupts many Van der Waal forces of interaction among other non-polar amino acid side chains  in the interior of the protein.
• This ultimately distorts the entire folding pattern of the protein causing its destabilisation and mis-folding.