{{tag>beta}}


====== 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 [[glossary:hydrogen_bond | hydrogen bond]] between the CO(i) and NH(i+3). There are several different types of beta turns (see references below).

===== References ====

{{pubmed>long:4351002}}
{{pubmed>long:4358939}}
{{pubmed>long:2865874}}
{{pubmed>long:2371257}}
{{pubmed>long:3184187}}
{{pubmed>long:7756980}}