Knobs into holes packing

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Knobs into holes packing is a protein folding motif that occurs mainly in alpha helix or coiled coil domains. One such example is fibrinogen fibril formation.

This motif occurs in coiled coil motifs to maintain and reach a 20 degree "left hand crossing angle that is characteristic of coiled coils". This motif looks much like two springs slammed together. (See also Helix bundle)

Alpha helix is little tighter packed in knobs into holes packing, having on average 3.5 amino acid residues per turn. Side chains are packed in the gaps of the complementary alpha helix and these helices are parallel to each other.

Further reading[edit]

  1. Cryst
  2. Blood Journal


  • Embase Eilers M., Patel A.B., Liu W. and Smith S.O. (2002). "Comparison of helix interactions in membrane and soluble alpha-bundle proteins." Biophysical Journal. 82(5) (pp 2720–2736).

Biochemistry. 2009 Sep 15;48(36):8656-63. Impaired protofibril formation in fibrinogen gamma N308K is due to altered D:D and "A:a" interactions. Bowley SR, Okumura N, Lord ST. Source

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.