Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russian Federation.
Biochem Biophys Res Commun. 2010 Aug 27;399(3):412-5. doi: 10.1016/j.bbrc.2010.07.089. Epub 2010 Jul 30.
Beta-hairpins, triple-strand beta-sheets and betaalphabeta-units represent simple structural motifs closed into cycles by systems of hydrogen bonds. Secondary closing of these simple motifs into large cycles by means of different superhelices, split beta-hairpins or SS-bridges results in the formation of more complex structural motifs having unique overall folds and unique handedness such as abcd-units, phi-motifs, five- and seven-segment alpha/beta-motifs. Apparently, the complex structural motifs are more cooperative and stable and this may be one of the main reasons of high frequencies of occurrence of the motifs in proteins.
β发夹、三股β-折叠和ββα-单元通过氢键系统环化形成简单的结构基序。这些简单基序通过不同的超螺旋、分裂β发夹或 SS 桥的次级环化形成具有独特整体折叠和独特手性的更复杂结构基序，如 abcd-单元、φ 基序、五段和七段 α/β-基序。显然，复杂结构基序更具协同性和稳定性，这可能是这些基序在蛋白质中高频率出现的主要原因之一。
