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Gamma turns

A Gamma turn is defined for 3 residues i, i+1, i+2 if a hydrogen bond exists between residues i and i+2 and the phi and psi angles of residue i+1 fall within 40 degrees of one of the following 2 classes (Rose et al., 1985, Milner-White et al., 1988):

turn type              phi(i+1)                psi(i+1)
classic                 75.0                    -64.0
inverse                -79.0                     69.0

Plots

The plots for each turn show a Ramachandran plot with residue i+1 plotted on it ( green dot). Below is a schematic plot of the turn with the 3 residues and the Calpha(i)-Calpha(i+2) distance marked and arrows to indicate the i to i+2 hydrogen bond. The residue numbers and turn type are indicated above the Ramachandran plot.

A PostScript or PDF version of the plots (showing 16 turns per page) can be generated by clicking on the appropriate icon below the Table.

Table

The following data are given for each gamma turn in the protein chain: the start and end residues of the gamma turn (residues i and i+2), the amino acid sequence of the residues in the turn and the turn type. Phi, psi and chi1 dihedral angles are given for the central residue (i+1). The final column gives the distance between the Calpha atoms of residues i and i+2.

References

Milner-White EJ, Ross BM, Ismail R, Belhadj-Mastefa K and Poet R (1988). One type of gamma turn, rather than the other, gives rise to chain reversal in proteins. J. Mol. Biol., 204, 777-782.
Rose GD, Gierasch LM and Smith JA (1985). Turns in peptides and proteins. Adv. Prot. Chem., 37, 1-109.

 

Gail Hutchinson 22nd May, 1996 spacer
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