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cat-liujiang鐵桿木蟲 (正式寫手)
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[求助]
求教:GC-MS同位素標記定量 已有1人參與
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請教一個問題,看到一篇文獻,做的同位素標記前體物飼喂,最后用GC-MS檢測同位素標記的代謝物含量 這些化合物的分子量與他們標記的 target ion差別很大 比如第一個化合物分子量是89,3個碳都同位素標記后,應(yīng)該是92啊,但他的target ion卻是221 所有化合物似乎都對不上號,不知道是咋回事兒 Supp. Table 3. Metabolites identified in RCH2 bacterial lysates and their corresponding 13C target ion used for recovery comparison, retention time (RT) and RT of authentic standards. Putative metabolite annotations are indicated by italics (retention time and/or spectra could not be confirmed with an authentic standard). Compound 13C target ion Chemical Formula alanine 221 C3H7NO2 valine 220 C5H11NO2 isoleucine 163 C6H13NO2 proline 146 C5H9NO2 glycine 249 C2H5NO2 uracil 245 C4H4N2O2 serine 206 C3H7NO3 用的是安捷倫的氣質(zhì) Agilent 7890 gas chromatograph (Agilent Technologies, Santa Clara, CA) Agilent 5977 single quadrupole mass spectrometer (MS) http://www.sciencedirect.com/sci ... 71714003502#appsec1 3.5. Microbial metabolite adsorption and recovery To explore the types of microbial metabolites that adsorb to soil and therefore may represent those that are unavailable to microbes in situ, 13C-labeled RCH2 bacterial lysates were incubated with soil and extracted with water (Fig. 3). K2SO4 (10 mM) was compared to water to determine if this classical extractant was more efficient at metabolite recovery. The most intense peaks from the unlabeled RCH2 lysates (grown with 12C-acetate) were selected for further analysis in labeled samples (compound identification, 13C incorporation and recovery calculations). Spectra from unlabeled RCH2 were compared to labeled cultures, which resulted in the identification of 45 fully-labeled metabolites (Fig. 4, Supp. Table 3). The 13C target ion for each metabolite was quantified for all samples and recovery was calculated. Only 27% of the quantified metabolites showed >50% recovery in the WEOM, with the majority of those being neutral metabolites. All of the polyamine cations identified in this experiment (putrescine, cadaverine, lysine, spermine and spermidine) and most of the anionic metabolites were among those that adsorbed rapidly to soil (Fig. 4). The inclusion of 10 mM K2SO4 as a recovery extractant did not drastically improve or reduce recovery compared to water alone. |
鐵桿木蟲 (正式寫手)

新蟲 (小有名氣)
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gcms測量的是分子量,所以當然可以測出c13 標記的化合物。實際上有的醫(yī)院就用質(zhì)譜測定c13標記的二氧化碳(用碳十三標記的尿素讓檢測者服用,可以測定有無幽門螺桿菌細胞內(nèi)起催化作用的尿素分解酶) 發(fā)自小木蟲Android客戶端 |
新蟲 (小有名氣)
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