Question

What are the two types of beta sheets?

Answer 1

Hint: The beta-sheet is a type of typical secondary structural motif found in normal proteins. The Beta sheets are made up of beta strands that are joined laterally by at least two or three backbone hydrogen bonds to form a twisted, pleated sheet. A beta-strand is a polypeptide chain that is typically composed of 3 to 10 amino acids and has an extended backbone. In other words, a beta-sheet is a local 3D conformation of amino acids that are found in close proximity with each other in their linear sequences. Beta sheet and alpha structure is a type of secondary structural motif of protein.

Complete Step by Step Solution:
All the strands run in one direction in parallel beta-sheets. While in the antiparallel sheets they all run in opposite directions. Sheets usually prefer to be all parallel or all antiparallel in nature, although there are some mixed sheets. The beta-Pauling-Corey sheet’s model is planar (on a plane surface).

From repeating structural units consisting of two or three short beta-strands connected by short loops, a beta-helix is formed. These units repeatedly form a hydrogen connection with one another as they "stack" in a helical pattern above one another in a parallel orientation.

Two peptide strands flowing in the same direction are characterised by the Parallel Beta-Sheet, held together by hydrogen bonding between the strands. The beta-sheet is formed by hydrogen bonds between protein strands, rather than inside a strand, unlike the alpha helix. As the hydrogen bonding pattern is more optimum, anti-parallel beta sheets are significantly more robust than parallel beta sheets. Hydrogen bonds between the strands reflect the green lines.

Note: A beta-sheet is a protein structure proposed by Linus Pauling and Robert Corey in the year 1951. The name Beta was chosen because it was their second proposed structure after the alpha helix (it was their first). It is necessary for the structure of proteins that bind to the fatty acids required for lipid metabolism.