Repetitive peptide segment & β-sheet
Displayed here is a peptide segment that is present in many fibroin proteins that are found in silk fibers. () It is repeated many times to make up the ordered, repetitive structure of the crystalline domain of the fibroin.
Determine the sequence of the segment by hovering over the residues taking time to consider the nature of their side chains and from which direction their side chains project from the backbone. All the Gly need to be on the same side of the peptide in order to construct the silk fiber. Labels describe how additional are added to the ends of this peptide segment to produce the longer polypeptide.
A two strand β-sheet is formed by positioned antiparallel with respect to each other. Shown in .
A four stranded . Shown in .
