A new LC-MS method has been established for determination of momoiodotyrosine(MIT) and diiodotyrosine(DIT) in the hydrolysate of premix feeds.Samples was hydrolyzed with 4.0 mol·L-1 NaOH for 16 h at 110 ℃,then t...A new LC-MS method has been established for determination of momoiodotyrosine(MIT) and diiodotyrosine(DIT) in the hydrolysate of premix feeds.Samples was hydrolyzed with 4.0 mol·L-1 NaOH for 16 h at 110 ℃,then the hydrolysate was cleaned up with a SPE cartridge and injected directly for LC-MS analysis.Chromatographic separation was performed on a 2.1 mm×150 mm,5 μm particle,C18 column with a mixture of acetonitrile and 0.1%(by volume) acetic acid as mobile phase at a flow rate of 0.2 mL· min-1.ESI+ mass spectrometry detection was run on SIR mode with m/z 308,262 for MIT,and m/z 434,388 for DIT.Quantification was carried out with external standard method.Validation data indicated the method was linear in the concentration ranges investigated with regression coefficients(R2) of more than 0.99.The limits of detection(LOD) were 8 μg·L-1 and limits of quantification(LOQ) were 30 μg·L-1.The recoveries were range of 93%-110% with relative standard deviations of 6.5%-13.2%.The method was sensitive,accurate,and was applied in the determination of MIT and DIT in real sample with satisfactory results.展开更多
缺乏必需氨基酸,会通过抑制mRNA翻译的起始阶段而引起细胞内所有蛋白质合成的下降,但是不同蛋白质合成受抑制的程度并不相同。某些蛋白质,尤其是由具有5′末端寡嘧啶(5-t′erm ina l o ligopyrim id ine,TOP)特征的mRNA编码的蛋白质,其...缺乏必需氨基酸,会通过抑制mRNA翻译的起始阶段而引起细胞内所有蛋白质合成的下降,但是不同蛋白质合成受抑制的程度并不相同。某些蛋白质,尤其是由具有5′末端寡嘧啶(5-t′erm ina l o ligopyrim id ine,TOP)特征的mRNA编码的蛋白质,其受影响的程度要高于其余大多数蛋白质。TOP mRNA翻译的特异性下降,是核糖体蛋白S6激酶、S6K 1受抑制及S6磷酸化同时降低所致。由于许多TOP mRNA编码的蛋白质(如真核细胞延长因子eEF 1A和eEF 2以及核糖体蛋白质)参与mRNA的翻译,因此,必需氨基酸的缺乏不仅会快速、直接地抑制所有mRNA的翻译,而且会潜在地导致机体合成蛋白质的能力下降。所以持续供给完全平衡的必需氨基酸是使肝脏和骨骼肌中的蛋白质合成维持在最佳速度的先决条件。展开更多
文摘A new LC-MS method has been established for determination of momoiodotyrosine(MIT) and diiodotyrosine(DIT) in the hydrolysate of premix feeds.Samples was hydrolyzed with 4.0 mol·L-1 NaOH for 16 h at 110 ℃,then the hydrolysate was cleaned up with a SPE cartridge and injected directly for LC-MS analysis.Chromatographic separation was performed on a 2.1 mm×150 mm,5 μm particle,C18 column with a mixture of acetonitrile and 0.1%(by volume) acetic acid as mobile phase at a flow rate of 0.2 mL· min-1.ESI+ mass spectrometry detection was run on SIR mode with m/z 308,262 for MIT,and m/z 434,388 for DIT.Quantification was carried out with external standard method.Validation data indicated the method was linear in the concentration ranges investigated with regression coefficients(R2) of more than 0.99.The limits of detection(LOD) were 8 μg·L-1 and limits of quantification(LOQ) were 30 μg·L-1.The recoveries were range of 93%-110% with relative standard deviations of 6.5%-13.2%.The method was sensitive,accurate,and was applied in the determination of MIT and DIT in real sample with satisfactory results.
文摘缺乏必需氨基酸,会通过抑制mRNA翻译的起始阶段而引起细胞内所有蛋白质合成的下降,但是不同蛋白质合成受抑制的程度并不相同。某些蛋白质,尤其是由具有5′末端寡嘧啶(5-t′erm ina l o ligopyrim id ine,TOP)特征的mRNA编码的蛋白质,其受影响的程度要高于其余大多数蛋白质。TOP mRNA翻译的特异性下降,是核糖体蛋白S6激酶、S6K 1受抑制及S6磷酸化同时降低所致。由于许多TOP mRNA编码的蛋白质(如真核细胞延长因子eEF 1A和eEF 2以及核糖体蛋白质)参与mRNA的翻译,因此,必需氨基酸的缺乏不仅会快速、直接地抑制所有mRNA的翻译,而且会潜在地导致机体合成蛋白质的能力下降。所以持续供给完全平衡的必需氨基酸是使肝脏和骨骼肌中的蛋白质合成维持在最佳速度的先决条件。
