圓二色譜circulardichroism(cd)(參考版)
2025-07-21 18:01本頁面
【正文】 THANKS! 。 Anything optical active, . Glutamate Summary ? CD is a useful method for looking at secondary structures of proteins and peptides. ? CD is based on measuring a very small difference between two large signals must be done carefully ? the Abs must be reasonable max between ~ and ~. ? Quarts cells path lengths between cm and 10 cm. 1cm and cm mon ? have to be careful with buffers TRIS bad high UV abs ? Measure cell base line with solvent ? Then sample with same cell inserted same way around ? Turbidity kills filter solutions ? Everything has to be clean ? For accurate 2ndry structure estimation must know concentration of sample 核酸的 CD信息 BZ? Or ZB？ 建議濃度：在吸光值 510倍 圓二色譜在糖類化合物結(jié)構(gòu)分析中的應(yīng)用 ? 碳水化合物的結(jié)構(gòu)決定 CD的強(qiáng)度和形狀，而從 CD獲得的構(gòu)象信息的多少取決于樣品結(jié)構(gòu)的復(fù)雜程度； ? 對那些具有較好重復(fù)系列的糖類化合物而言， CD能提供更為可靠的空間結(jié)構(gòu)信息。 對多肽的判斷較差！ CD實驗要點 Determination of Protein Concentration 精確的方法有： 1 定量氨基酸分析； 2 用縮二脲方法測量多肽骨架濃度 或測氮元素的濃度 ； 3 在完全變性條件下測芳香氨基酸殘基的吸收，來確定蛋白質(zhì)的準(zhǔn)確濃度 . ? Not Acceptable: 1. Bradford Method. 2. Lowry Method. 3. Absorbance at 280 and/or 260 nm. Nitrogen flushing Flushing the optics with dry nitrogen is a must: ?Xe lamp has a quartz envelope, so if operated in air it’ll develop a lot of ozone, harmful for the mirrors ?below 195nm oxygen will absorb radiation HT plot ? The HT plot is very important, since readings above 600650V mean that not enough light is reaching the detector so a sample dilution or the use of shorter path cell are required. ? Furthermore the HT plot is in realty a single beam spectra of our sample, since there is a direct relation between HT and sample absorbance. By data manipulation HT conversion into absorbance and buffer baseline subtraction is possible. Alternativ
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