A parallel beta-sheet from the periplasmic phosphate-binding protein of E. coli.  What difference is there in the connections between the three parallel beta-strands in this protein and the connection between the antiparallel strands in the previous models?

  Spacefilling model of the sheet without side chains.

  Complete parallel beta sheet. Glycine is exempt from many steric constraints because it lacks a beta carbon. Because Gly residues have more conformational freedom than other residues, they are seldom found in the central portions of alpha-helices or beta-sheets. However, glycines are often found at the ends of these structures. Look for two Gly residues at the ends of the beta-strands in this parallel sheet.

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