Research Articles

Crystal structure of a synthetic triple-stranded alpha-helical bundle

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Science  26 Feb 1993:
Vol. 259, Issue 5099, pp. 1288-1293
DOI: 10.1126/science.8446897

Abstract

The x-ray crystal structure of a peptide designed to form a double-stranded parallel coiled coil shows that it is actually a triple-stranded coiled coil formed by three alpha-helices. Unlike the designed parallel coiled coil, the helices run up-up-down. The structure is stabilized by a distinctive hydrophobic interface consisting of eight layers. As in the design, each alpha-helix in the coiled coil contributes one leucine side chain to each layer. The structure suggests that hydrophobic interactions are a dominant factor in the stabilization of coiled coils. The stoichiometry and geometry of coiled coils are primarily determined by side chain packing in the solvent-inaccessible interior, but electrostatic interactions also contribute.