Proteins (alpha-Helices and beta-Sheets)
The bonds formed by the connection of proteinogenic amino acids force the peptide chain to adopt either a helical structure or to form a zig-zag chain, which aggregate via hydrogen bonds to so-called beta sheets.
Alpha helix: |
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Beta sheet: |
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In real proteins, especially in large proteins, a combination of these two building blocks is usually found. A good example is the relatively small protein Amylase, which is found as a starch degrading enzyme in saliva.