分子生物物理學(xué)(存儲(chǔ)版)
【正文】 enIdealthosearemodel.ormajorityalphahelix7) / ideal(,secondarySecondary Structure 1951,Waals(W) interaction Relation with Energy and distancechargercharge rbetweensidechainsaminoProteinStructureTertiaryStructurePrimaryofofbasedPauling)omegaderbond OH XHydrogen bonds can vary in strength from very weak (12 kJ mol?1) to extremely strong (40 kJ mol?1), so strong as to be indistinguishable from a covalent bond, as in the ion HF2?. Typical values include:O—H...:N (7 kcal/mol) O—H...:O (5 kcal/mol) N—H...:N (3 kcal/mol) N—H...:O (2 kcal/mol) Proteinof+/the phi and psi angles of the alpha helix lie in the center of an allowed, minimum energy region of the Ramachandran (phi, psi) map. Why i(i+4)? interactions between i and i+4 stabilize helixDistortions of ahelices ThecurvedPaulingCoreyresiduesallbonds.)COHNGlyProintroductionThe pi helix is an extremely rare secondary structural element in proteins. the backbone C=O of residue i hydrogen bonds to the backbone HN of residue i+5.iwheelsecondaryI’Other3Dstructure(a). Homology. If sequence 2530%, structure similarity(b). Statistical. Chou 。 結(jié)構(gòu)域之間常常只有一段柔性的肽鏈連接，形成所謂鉸鏈區(qū)，使結(jié)構(gòu)域容易發(fā)生相對(duì)運(yùn)動(dòng)，這是結(jié)構(gòu)域的一大特點(diǎn)。這些獨(dú)立的三級(jí)結(jié)構(gòu)稱為亞基或亞單位。目前已經(jīng)測(cè)出三級(jí)結(jié)構(gòu)的生物大分子都儲(chǔ)存在蛋白質(zhì)數(shù)據(jù)庫(kù)中（Protein data bank,PDB)，借助軟件可查閱顯示其空間結(jié)構(gòu)，還可以在不同方向旋轉(zhuǎn)以獲得空間結(jié)構(gòu)的細(xì)節(jié)。? 例如紅氧還蛋白，核糖核酸酶、肌紅蛋白等。Edmundson (1967) Motif domain超二級(jí)結(jié)構(gòu)超二級(jí)結(jié)構(gòu) motif相鄰的二級(jí)結(jié)構(gòu)單元組合在一起，相鄰的二級(jí)結(jié)構(gòu)單元組合在一起，彼此相互作用，排列形成規(guī)則的、彼此相互作用，排列形成規(guī)則的、在空間結(jié)構(gòu)上能夠辨認(rèn)的二級(jí)結(jié)構(gòu)在空間結(jié)構(gòu)上能夠辨認(rèn)的二級(jí)結(jié)構(gòu)組合體，并充當(dāng)三級(jí)結(jié)構(gòu)的構(gòu)件（組合體，并充當(dāng)三級(jí)結(jié)構(gòu)的構(gòu)件（block building)，成為超二級(jí)結(jié)，成為超二級(jí)結(jié)構(gòu)，介于二級(jí)結(jié)構(gòu)與結(jié)構(gòu)域之間的構(gòu)，介于二級(jí)結(jié)構(gòu)與結(jié)構(gòu)域之間的結(jié)構(gòu)層次。constant:ofandsheetTwistsabout 30 degrees per residue in righthanded senseLefthanded: crossover angelRighthanded: progressive Hbond twistParallel sheets are less twisted than antiparallel and are always buried.BulgesBetahairpi
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