Question

Which of the following is not correct about the β-sheet?

(a) A β-sheet is a fully extended configuration built up from several spatially adjacent regions of a polypeptide chain

(b) Each region involved in forming the β-sheet is a β-strand

(c) The β-strand conformation is pleated with main chain backbone zigzagging and side chains positioned on same sides of the sheet

(d) β-Strands are stabilized by hydrogen bonds between residues of adjacent strands

I had been asked this question in an online quiz.

Question is taken from Protein Structure Basics in section Structural Bioinformatics of Bioinformatics

Answer 1

The correct option is (c) The β-strand conformation is pleated with main chain backbone zigzagging and side chains positioned on same sides of the sheet

Easy explanation: The β-strand conformation is pleated with main chain backbone zigzagging and side chains positioned alternately on opposite sides of the sheet. β-strands near the surface of the protein tend to show an alternating pattern of hydrophobic and hydrophilic regions, whereas strands buried at the core of a protein are nearly all hydrophobic. The β-strands can run in the same direction to form a parallel sheet or can run every other chain in reverse orientation to form an antiparallel sheet or a mixture of both.