Question

Describe the \(\beta\) -pleated structure present in some proteins.

Short answer

The beta-pleated sheet is a secondary structure found in proteins. Formed by beta strands connected by hydrogen bonds, this structure can either be parallel or antiparallel. The side chains in a beta-pleated sheet extend above and below the plane of the sheet, allowing for maximum interaction and minimal steric clashes. Beta-pleated sheets are common in many proteins and contribute to their strength and flexibility.

Step-by-step solution

Definition

Start by defining the beta-pleated sheet as a secondary structure found in proteins. This structure is formed by beta strands connected laterally by two or three backbone hydrogen bonds, forming a broader pleated sheet.

Strand directionality

Discuss the directionality of the strands. The beta-pleated sheet can be parallel, where all component strands run in the same direction, or antiparallel, where the direction alternates.

Hydrogen bonding

Detail the role of hydrogen bonds. These bonds are formed between the carbonyl oxygen of one peptide bond and the hydrogen on the nitrogen atom of another peptide bond, forming a bonding network that stabilizes the sheet structure.

Side chain positioning

Discuss the positioning of the side chains. The side chains (R groups) of the amino acid residues in a beta-pleated sheet extend above and below the plane of the sheet, minimizing steric clashes and maximizing interactions.

Function and examples

Finally, mention the significance of the beta-pleated sheet structure in protein function and its occurrence in nature. Beta-pleated sheets are found in many proteins, including silk and globular proteins, and provide strength and flexibility.