Okret (biohemija)
Okret je element sekundarne strukture proteina gde polipeptidni lanac menja sveukupnu orijentaciju. Po najčešće korišćenoj definiciji,[1] okret je strukturni motiv gde su Cα atomi dva ostatka razdvojena sa nekoliko (obično 1 do 5) peptidnih veza na maloj razdaljini (< 7 Å), dok korespondirajući ostaci ne formiraju regularni element sekundarne strukture, kao što je alfa heliks ili beta ravan. Za razliku od heliksa, diedral uglovi peptidne osnove nisu (aproksimativno) konstantni za sve ostatke okreta. Mada malo rastojanje između dva terminalna Cα atoma obično dovodi do formiranja jedne ili dve vodonične veze između korespondirajućih ostataka, takve vodonične veze nisu strogo neophodne za definisanje okreta.
Reference uredi
- ↑ Rose et al. 1985
Literatura uredi
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