The -pleated sheet conformations

Efforts to obtain characteristic CD spectra of antiparallel and parallel / -pleated sheet conformations have utilized the vacuum ultraviolet and drawn on infrared spectra to substantiate the two different states. It was found by Balcerski et al. [78] that films of Boc-(l Ala)7-OMe formed antiparallel )3-pleated sheets and films of Boc- 

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A second common pattern in the secondary structure of proteins is called the beta (yS )-pleated sheet (T Figure 19.10). In this structure, the chain is extended (as opposed to coiled) and forms a zigzag pattern like an accordion pleat. The peptide backbones of the chains interact with one another through hydrogen bonding to maintain the pleated sheet conformation. Some proteins—such as silk— have the )8-pleated sheet structure throughout their entire chain. Since its protein chains in the )8 -pleated sheet are fully extended, silk is inelastic. Many proteins, however, have some sections that are /3 -pleated sheet, other sections that are a-helix, and still other sections that have less regular patterns called random coils. 

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