Final answer:
Beta strands are held together by hydrogen bonding in a secondary structure known as the β-pleated sheet conformation, which is important in many structural proteins and enzymes.
Step-by-step explanation:
Beta strands in proteins are held together side by side by hydrogen bonding interactions between their backbones. This forms a secondary structure known as the β-pleated sheet conformation. These sheets consist of two or more extended polypeptide chains or different segments of a single chain that are aligned alongside each other.
They can run in parallel or antiparallel fashion, where the N-terminals of adjacent chains can face in the same or opposite directions. The β-pleated sheet is significant in many structural proteins, such as silk fibroin, and also appears in various enzymes, including carboxypeptidase A and lysozyme.