圓二色譜circulappt課件-閱讀頁
2025-05-21 23:20本頁面
【正文】 a c oil edcoilw a vele n g th in nm200 210 220 230 240MRE35302520151050TM 3 6 a qu eo usTM 3 6 + TFETFE? But on a coiledcoil breaks down helical dimer to single helices ? Although 2ndry structure same CD changes Effect of 50 % TFE o n a mo no me ri c pe pti dew av ele ngt h in nm200 210 220 230 240MRE35302520151050p e p ti d e i n w a te rp e p ti d e i n 5 0 % TFETFE? Can see this by looking at the effect of trifluoroethanol (TFE) on a coiledcoil similar to GCN4p1 ? TFE induces helicity in all peptides Best fitting procedures use many different proteins for standard spectra ? There are many different algorithms. ? All rely on using up to 20 CD spectra of proteins of known structure. ? By mixing these together a fit spectra is obtained for an unknown. ? For full details see Dichroweb: the online CD analysis tool ? Can generally get accuracies of for helices, for beta sheet, for turns, and for other structure types (Manavalan amp。 geometry. ? Far UV curves (275nm) can contain contributions from aromatic aminoacids, in practice CD is measured at wavelengths below this. ? The shapes of far UV CD curves depend on tertiary as well as secondary structure. 蛋白的三級結(jié)構(gòu) 1976年， Levitt和 Chothia曾在 Nature上報(bào)道，規(guī)則蛋白質(zhì)的三級結(jié)構(gòu)模型可分為 4類 (1) 全 α型，以僅 α螺旋結(jié)構(gòu)為主，其分量大于 40％ ，而β折疊的分量小于 5％ (2) 全 β型，以 β折疊這種結(jié)構(gòu)為主，其分量大于 40％ ，而僅一螺旋的分量小于 5％ ； (3) α+β型， α螺旋及 β疊折分量都大于 15％ ，這兩種結(jié)構(gòu)在空間上是分離的，且超過 60％的折疊鏈?zhǔn)欠雌叫信帕校? (4) α/β型， α螺旋和 B折疊含量都大于 15％ ，它們在空間上是相間的，且超過 60％的折疊鏈平行排列。 Vassilenko): 對全 a、 a /b和變性蛋白質(zhì)的準(zhǔn)確度為 100%， 對 a + b的準(zhǔn)確度為 85%， 對全 b的準(zhǔn)確度為 75%。 NaCl。 ? 對那些結(jié)構(gòu)比較復(fù)雜的糖類來說，即使不能直接測定糖類化合物的絕對構(gòu)象，利用一些經(jīng)驗(yàn)規(guī)則，例如，CD可以用來推斷糖類是否具有 gt構(gòu)象，而且 CD可以作為探針來測定糖類化合物構(gòu)象的變化，如膠體 溶液或無序 有序的
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