Supersecondary structure

From Wikipedia, the free encyclopedia

It has been suggested that this article or section be merged into Structural motif. (Discuss)

In 1976 only 56 protein structures were available in the PDB cite(bernstein1977), yet tertiary structure had already been generally classified into four secondary structure classes cite(levitt1976) and three different 'folding units' or supersecondary structures cite(lesk2001), speculated to be the 'building blocks' of tertiary structure cite(levitt1976,chothia1977). The prevalence of common secondary and supersecondary structures in proteins is explained by the thermodynamic stability conferred by these protein conformations cite(chothia1984,finkelstein1987). Thus, for any given amino-acid sequence, only a few stable secondary and supersecondary conformations are available. For a protein to reliably assume a functional topology in a biological system, these structural units can be converged on over the course of evolution as consistent `means to an overall functional end'.