Beta Link

Motif Glossary

Beta Link


A motif of four consecutive residues (tetrapeptide), a residue separate from these (singleton), and three H-bonds in which there is:

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The sub-categories distinguish the conformational variants of the Beta Turn, always found at residues-2 and -3, and whether the singleton is N-terminal (N-singleton) or C-terminal (C-singleton) to the tetrapeptide, primarily for analysis and graphical presentation.

Alternative visualization

It is more usual to present the β-link in a way that relates to the β-bulge, rather than the β-turn. This involves replacing the numbering from 1-to-4 by –1-to-2, and flipping the diagram above vertically and horizontally, with the singleton designated ‘X’:

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Leader and Milner-White, Acta Cryst. D77 217–223 (2021)

Leader and Milner-White, Acta Cryst. D77 1040–1049 (2021)


1. The Beta Link encompasses Beta Bulges of type 0,1,2-βRαLβR (G1β).

2. The Beta Link was previously listed here as ‘Beta Bulge Turn’ and then as ‘Beta Tether’.


Approx. 12% of Beta Bulges are parts of Beta Links.