Asx Turn

Motif Glossary

Asx Turn

Definition

A motif of three consecutive residues and one H-bond in which there is:

• Aspartate or Asparagine (Asx) at residue-1
• H-Bond between side-chain O of residue-1 and main-chain NH of residue-3.

Sub-categories

These encompass the following conformations for each of Asp and Asn:

• 1,2-χ60αR (aka: type I or R-handed)
• 1,2-χ60αL (aka: type II or R-handed flipped)
• 1,2-χ180αL (aka: type I' or L-handed)
• 1,2-χ180αR (aka: type II' or L-handed flipped)

Reference

Duddy and Milner-White, Protein Sci. 13:3051-3055 (2004)

Comments

1. The Asx Turn, like the ST Turn, resembles the H-bonded Beta Turn in the sense that side-chain atoms of residue-1 mimic the main-chain of residue-1 of Beta Turns.

2. The previous definition of subcategories specified subsections of the βR region at residue-1. The current definition in terms of the χ1 angle of the side-chain is more intuitive, although its effect is the same as the old definition.

Introduction AlphaBeta Loop Asx Motif Asx Turn Beta Bulge Beta Bulge Loop Beta Link Beta Turn BulgeLoop Motif Crown Bridge Crown Bridge Loop Nest Niche Schellman Loop ST Loop ST Motif ST Staple ST Turn