Crown Bridge Loop

Motif Glossary

Crown Bridge Loop

Definition

A motif of six consecutive amino acid residues and two H-bonds in which:

• Dihedral angles are 4,5-sub-αRαR (sub-αR encompases the bottom left quadrant of the Ramachandran plot)
• H-Bonds are made between the NHs of both residue-4 and residue-6 and the CO of residue-1.

Sub-categories

These distinguish the different conformational variants of the Beta Turn, always found at residues 1–4 of a Crown Bridge Loop.

• 2,3-αRαR
• 2,3-βRαL
• 2,3-αLαL
• 2,3-βLαR

Reference

Leader and Milner-White, Proteins 83:2067–2076 (2015)

Comments

1. Crown Bridge Loops are also Crown Bridges. They are presented separately to allow all six residues to be shown.

2. No examples of Crown Bridge Loops encompassing left-handed Beta Turns were found in the database.

Occurrence

Crown Bridge Loops are relatively rare. Many of them are found near the C-termini of α-helices.

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