圓二色譜circulardichroism(cd)-展示頁
2025-07-27 18:01本頁面
【正文】 UVVIS spectra. ?CD spectroscopy calls for same requirements as UVVIS: best S/N is obtained with absorbance level in the range to . It’s usually difficult to get proper data when absorbance (of sample + solvent) is over 2 . Typical Conditions for protein CD ? Protein Concentration: mg/ml ? Cell Path Length: 1 mm ? Volume 350 ml ? Need very little sample mg ? Concentration reasonable ? Stabilizers (Metal ions, etc.): minimum ? Buffer Concentration : 5 mM or as low as possible while maintaining protein stability 溶劑的吸收 !!! Buffer Systems for CD Analyses ?Acceptable: 1. Potassium Phosphate with KF, K2SO4 or (NH4)2SO4 as the salt. 2. Hepes, 2mM. 3. Ammonium acetate, 10mM. ?Avoid: Tris。 CD signal of a protein depends on its 2ndary structure —— chymotrypsin (all b) —— lysozyme (a + b) —— triosephosphate isomerase(a/b) —— myoglobin (all a) 從 CD譜分析蛋白質(zhì)的結(jié)構(gòu)類型 (Venyaminov amp。 Johnson, 1987, Anal. Biochem. 167, 7685). 估算蛋白質(zhì) a螺旋 含量 僅適合 a含量較高的蛋白質(zhì)！ *Yang算法 Limitations of CD secondary structure analysis ? The simple deconvolution of a CD spectrum into 4 or 5 ponents which do not vary from one protein to another is a gross oversimplification. ? The reference CD spectra corresponding to 100% helix, sheet, turn etc are not directly applicable to proteins which contain short sections of the various structures . The CD of an αhelix is known to increase with increasing helix length, CD of βsheets are very sensitive to environment amp。 近紫外 CD譜可作為一種靈敏的光譜探針，反映 Trp、Tyr和 Phe及二硫鍵所處微環(huán)境的擾動，能用來研究蛋白質(zhì)三級結(jié)構(gòu)精細(xì)變化。 is always optically active 蛋白質(zhì)的光學(xué)活性 蛋白質(zhì)的 CD譜 ?CD spectra in the far UV region (180 nm – 250 nm) probes the secondary structures of proteins. ?CD spectra in the near UV region (~250 and ~ 350) monitors the side chain tertiary structures of protei
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