Beta Turn

A beta turn occurs where the polypeptide chain makes a sharp reversal by 180 degrees within 4 residues. A turn is defined by 4 consecutive residues (i to i+3) if the C-alpha(i) to C-alpha(i+3) distance is less than 7 angstroms, and if the central two residues are not helical. There is often a hydrogen bond between the CO(i) and NH(i+3). There are several different types of beta turns (see references below).


Chain reversals in proteins.
Lewis PN, Momany FA, Scheraga HA
Biochim Biophys Acta303p211-29(1973 Apr 20)
Turns in peptides and proteins.
Rose GD, Gierasch LM, Smith JA
Adv Protein Chem37p1-109(1985)
Beta-turns and their distortions: a proposed new nomenclature.
Wilmot CM, Thornton JM
Protein Eng3p479-93(1990 May)
Analysis and prediction of the different types of beta-turn in proteins.
Wilmot CM, Thornton JM
J Mol Biol203p221-32(1988 Sep 5)
A revised set of potentials for beta-turn formation in proteins.
Hutchinson EG, Thornton JM
Protein Sci3p2207-16(1994 Dec)