1. The α helix, β strand and sheet, and turn are the most prevalent elements of protein secondary structure, which is stabilized by hydrogen bonds between atoms of the peptide backbone

2. Protein tertiary structure results from hydrophilic ionic interactions between polar side groups and hydrogen bonds between polar side groups that stabilize folding of the secondary structure into a compact overall arrangement, or conformation

3. Large proteins often contain distinct domains, independently folded regions of tertiary structure with characteristic structural or functional properties or both. The incorporation of domains as modules in different proteins in the course of evolution has generated diversity in protein structure and function

4. Quaternary structure encompasses the number and organization of subunits in multimeric proteins Which of the following statement is correct in relation to protein folding and its higher level structures?

• (A) 1 and 2
• (B) 2, 3 and 4
• (C) 1, 3 and 4
• (D) All of the above

Solution

1. True: The α-helix, β-strand and sheet, and turn are the most prevalent elements of protein secondary structure, which is stabilized by hydrogen bonds between atoms of the peptide backbone.

2. True: Protein tertiary structure results from hydrophilic ionic interactions between polar side

groups and hydrogen bonds between polar side groups that stabilize folding of the secondary structure into a compact overall arrangement or conformation.

3. True: Large proteins often contain distinct domains, independently folded regions of tertiary structure with characteristic structural or functional properties or both. The incorporation of domains as modules in different proteins in the course of evolution has generated diversity in protein structure and function.