建立了基于实时直接分析质谱(direct analysis in real time mass spectrometry,DART-MS)快速测定牦牛肉中羧甲基赖氨酸[N^(ε)-(carboxymethyl)lysine,CML]、羧乙基赖氨酸[N^(ε)-(carboxyethyl)lysine,CEL]含量的方法,并探究了苦荞、...建立了基于实时直接分析质谱(direct analysis in real time mass spectrometry,DART-MS)快速测定牦牛肉中羧甲基赖氨酸[N^(ε)-(carboxymethyl)lysine,CML]、羧乙基赖氨酸[N^(ε)-(carboxyethyl)lysine,CEL]含量的方法,并探究了苦荞、藤椒抗氧化食品原料对牦牛肉中羧基赖氨酸含量的影响。在正离子模式下,采用三重四级杆多反应监测模式,对CML在DART-MS的裂解机制进行了系统研究,并对DART离子源的气体解吸温度、栅网电极电压等试验条件进行了优化。结果表明,CML质量浓度在1~50μg/mL与峰面积呈现良好线性关系。CML的检测限为0.1μg/g,定量限为0.5μg/g,回收率为100.77%~117.36%,精密度为8.22%~9.87%。该方法能在2 min内完成8个/批样品中CML、CEL的快速检测。加入牦牛肉质量50%的苦荞粉后,牦牛肉中CML、CEL含量分别降低7.72%和1.46%;加入牦牛肉质量50%的藤椒粉后牦牛肉中CML降低14.51%,CEL增加7.35%。研究结果可为开发高品质牦牛肉产品提供理论依据。展开更多
食源性晚期糖基化终末产物(advanced glycation end products,AGEs)与多种慢性疾病密切相关,尤其是糖尿病和肾脏疾病。为减少AGEs对机体的健康风险,降低食品中AGEs含量,本研究从13种氨基酸中筛选出具有良好AGEs抑制效果的色氨酸(tryptop...食源性晚期糖基化终末产物(advanced glycation end products,AGEs)与多种慢性疾病密切相关,尤其是糖尿病和肾脏疾病。为减少AGEs对机体的健康风险,降低食品中AGEs含量,本研究从13种氨基酸中筛选出具有良好AGEs抑制效果的色氨酸(tryptophan,Trp),利用牛血清白蛋白(bovine serum albumin,BSA)-果糖、BSA-丙酮醛(methylglyoxal,MGO)、BSA-乙二醛(glyoxal,GO)和精氨酸(arginine,Arg)-MGO模型探究Trp对AGEs的抑制机理。结果表明,Trp对荧光AGEs的抑制呈现出显著的质量浓度依赖性。在BSA-GO模型中Trp抑制效果最佳,其次是BSA-MGO模型和Arg-MGO模型,而在BSA-果糖模型中抑制效果不明显。Trp对N^(ε)-羧甲基赖氨酸(N^(ε)-carboxymethyllysine,CML)和N^(ε)-羧乙基赖氨酸(N^(ε)-carboxyethyllysine,CEL)的抑制呈现钟形曲线,在1000μg/mL下对CML和CEL的抑制率最高。通过探究Trp捕获MGO的能力发现,其可通过芳香亲电子取代和PictetSpengler反应捕获MGO,最高捕获能力为3 mol。展开更多
Advanced glycation end-products （AGEs） are products of non-enzymatic glycation of proteins, lipids or nucleic acids and other macromolecules. To be spe- cific, Nε-（carboxymethyl）-Iysine （CML） is one of the most...Advanced glycation end-products （AGEs） are products of non-enzymatic glycation of proteins, lipids or nucleic acids and other macromolecules. To be spe- cific, Nε-（carboxymethyl）-Iysine （CML） is one of the most important components of AGEs, which is wildly distributed in the body and can be formed in vivo or in food processing and heating processes. Previous studies have shown that CML is a ma- jor immunological epitope in AGEs and plays an important role in diabetes and its complications, as well as in the development and progression of aging. This review summarized recent advances in major source, toxicological hazard and control mea- sures of CML.展开更多
The Polybromo （PB） protein functions as a key component of the human PBAF chromatin remodeling complex in regulation of gene transcription. PB is made up of modular domains including six bromodomains that are known ...The Polybromo （PB） protein functions as a key component of the human PBAF chromatin remodeling complex in regulation of gene transcription. PB is made up of modular domains including six bromodomains that are known as acetyl-lysine binding domains. However, histone-binding specificity of the bromodomains of PB has remained elusive. In this study, we report biochemical characterization of all six PB bromodomains＇ binding to a suite of lysine-acetylated peptides derived from known acetylation sites on human core histones. We demonstrate that bromodomain 2 of PB preferentially recognizes acetylated lysine 14 of histone H3 （H3K14ac）, a post-translational mark known for gene transcriptional activation. We further describe the molecular basis of the selective H3K14ac recognition of bromodomain 2 by solving the protein structures in both the free and bound forms using X-ray crystallography and NMR, respectively.展开更多
文摘建立了基于实时直接分析质谱(direct analysis in real time mass spectrometry,DART-MS)快速测定牦牛肉中羧甲基赖氨酸[N^(ε)-(carboxymethyl)lysine,CML]、羧乙基赖氨酸[N^(ε)-(carboxyethyl)lysine,CEL]含量的方法,并探究了苦荞、藤椒抗氧化食品原料对牦牛肉中羧基赖氨酸含量的影响。在正离子模式下,采用三重四级杆多反应监测模式,对CML在DART-MS的裂解机制进行了系统研究,并对DART离子源的气体解吸温度、栅网电极电压等试验条件进行了优化。结果表明,CML质量浓度在1~50μg/mL与峰面积呈现良好线性关系。CML的检测限为0.1μg/g,定量限为0.5μg/g,回收率为100.77%~117.36%,精密度为8.22%~9.87%。该方法能在2 min内完成8个/批样品中CML、CEL的快速检测。加入牦牛肉质量50%的苦荞粉后,牦牛肉中CML、CEL含量分别降低7.72%和1.46%;加入牦牛肉质量50%的藤椒粉后牦牛肉中CML降低14.51%,CEL增加7.35%。研究结果可为开发高品质牦牛肉产品提供理论依据。
基金Supported by "Twelfth Five-Year" National Science and Technology Support Project of China(2012BAK01B03)National 863 Plan(2013AA102202)~~
文摘Advanced glycation end-products （AGEs） are products of non-enzymatic glycation of proteins, lipids or nucleic acids and other macromolecules. To be spe- cific, Nε-（carboxymethyl）-Iysine （CML） is one of the most important components of AGEs, which is wildly distributed in the body and can be formed in vivo or in food processing and heating processes. Previous studies have shown that CML is a ma- jor immunological epitope in AGEs and plays an important role in diabetes and its complications, as well as in the development and progression of aging. This review summarized recent advances in major source, toxicological hazard and control mea- sures of CML.
文摘The Polybromo （PB） protein functions as a key component of the human PBAF chromatin remodeling complex in regulation of gene transcription. PB is made up of modular domains including six bromodomains that are known as acetyl-lysine binding domains. However, histone-binding specificity of the bromodomains of PB has remained elusive. In this study, we report biochemical characterization of all six PB bromodomains＇ binding to a suite of lysine-acetylated peptides derived from known acetylation sites on human core histones. We demonstrate that bromodomain 2 of PB preferentially recognizes acetylated lysine 14 of histone H3 （H3K14ac）, a post-translational mark known for gene transcriptional activation. We further describe the molecular basis of the selective H3K14ac recognition of bromodomain 2 by solving the protein structures in both the free and bound forms using X-ray crystallography and NMR, respectively.
