A combined gas chromatography combustion-isotope ratio mass spectrometry method(GC-C IRMS) for stable carbon isotope analysis of amino acids is presented. Unlike hydrocarbons, amino acids require derivatization prior ...A combined gas chromatography combustion-isotope ratio mass spectrometry method(GC-C IRMS) for stable carbon isotope analysis of amino acids is presented. Unlike hydrocarbons, amino acids require derivatization prior to GC-C-IRMS analysis. Replicate carbon isotope analyses of trifluoroacetyl isopropyl ester derivatives of 17 amino acids by IRMS revealed that the derivatization process is reproducible. Due to a reproducible isotopic fractionation an empirical correction factor for each individual amino acid is derived separately for derivatives and the original δ^13C value of the underivatized amino acid is calculated.展开更多
目的:随着生物医学迅猛的发展,更多的新技术新方法被引入实验室,并逐步应用于人体超微结构与功能的研究,其中多肽、氨基酸单体的生物活性研究愈加受到有关课题的重视。并且多学科的渗透和多技术的交叉已形成新的模式,鉴定其结构的性质...目的:随着生物医学迅猛的发展,更多的新技术新方法被引入实验室,并逐步应用于人体超微结构与功能的研究,其中多肽、氨基酸单体的生物活性研究愈加受到有关课题的重视。并且多学科的渗透和多技术的交叉已形成新的模式,鉴定其结构的性质分析手段亦跃升到借助物理化学等高新技术,通过物质本身官能团的多组信息进行特征分析。方法:根据构成蛋白质骨架的主要原素——氢具有产生磁矩、有自旋能力的特性,采用Nuclear magnetic resonance—NMR核磁共振(氢)波谱技术,对L-CLY等19种氨基酸进行了研究。结果:15种氨基酸的波谱特征表达与国外相关研究十分吻合,并且首次获得L.D—His和L.D—Trp4种氨基酸的结构信息。结论:本组研究设立HMR分析条件:脉宽PW=5.8,增益RG=26,驰豫=0.2.采样NS=36,谱宽SW=4000Hz,偏置01=3800条。实验证明能满足分析需要。展开更多
The formation of dipeptides from amino acids can be driven by hydroxyapatite at a relatively low temperature in air. For example, the formation of (Ala)2 from Ala is induced on hydroxyapatite at 110°C with consid...The formation of dipeptides from amino acids can be driven by hydroxyapatite at a relatively low temperature in air. For example, the formation of (Ala)2 from Ala is induced on hydroxyapatite at 110°C with considerable yield. Typically, condensing agents, high temperatures (>250°C) or high pressures (>25 MPa) are required to drive the condensation of amino acids. Similar effects are observed in the condensation of Gly, Glu and Asp. Experiments demonstrate that hydroxyapatite is an effective inorganic catalytic agent, reducing the activation barrier for the formation of dipeptides by more than 50%. HAP promotes condensation by adsorbing amino acid monomers in an organized manner, which decreases the distance between amino and carboxyl groups on neighboring molecules and extends the contact time of the reaction groups. This work provides a chemical understanding of the primitive condensation of amino acids and reveals a mechanism for enhancement of mineral catalysts. It is important that the conditions used for hydroxyapatite-assisted dipeptide formation are not harsh and can be readily achieved, revealing a possible mechanism for the chemical evolution of biomolecules over geologic ages.展开更多
The detection of single amino-acid variants （SAVs） usually depends on single-nucleotide polymorphisms （SNPs） database. Here, we describe a novel method that discovers SAVs at proteome level independent of SNPs dat...The detection of single amino-acid variants （SAVs） usually depends on single-nucleotide polymorphisms （SNPs） database. Here, we describe a novel method that discovers SAVs at proteome level independent of SNPs data. Using mass spectrometry-based de novo sequencing algorithm, peptide-candidates are identified and compared with theoretical protein database to generate SAVs under pairing strategy, which is followed by database re-searching to control false discovery rate. in human brain tissues, we can confidently identify known and novel protein variants with diverse origins. Combined with DNA/RNA sequencing, we verify SAVs derived from DNA mutations, RNA alternative splicing, and unknown post-transcriptional mechanisms. Furthermore, quantitative analysis in human brain tissues reveals several tissue-specific differential expressions of SAVs. This approach provides a novel access to high-throughput detection of protein variants, which may offer the potential for clinical biomarker discovery and mechanistic research.展开更多
文摘A combined gas chromatography combustion-isotope ratio mass spectrometry method(GC-C IRMS) for stable carbon isotope analysis of amino acids is presented. Unlike hydrocarbons, amino acids require derivatization prior to GC-C-IRMS analysis. Replicate carbon isotope analyses of trifluoroacetyl isopropyl ester derivatives of 17 amino acids by IRMS revealed that the derivatization process is reproducible. Due to a reproducible isotopic fractionation an empirical correction factor for each individual amino acid is derived separately for derivatives and the original δ^13C value of the underivatized amino acid is calculated.
文摘目的:随着生物医学迅猛的发展,更多的新技术新方法被引入实验室,并逐步应用于人体超微结构与功能的研究,其中多肽、氨基酸单体的生物活性研究愈加受到有关课题的重视。并且多学科的渗透和多技术的交叉已形成新的模式,鉴定其结构的性质分析手段亦跃升到借助物理化学等高新技术,通过物质本身官能团的多组信息进行特征分析。方法:根据构成蛋白质骨架的主要原素——氢具有产生磁矩、有自旋能力的特性,采用Nuclear magnetic resonance—NMR核磁共振(氢)波谱技术,对L-CLY等19种氨基酸进行了研究。结果:15种氨基酸的波谱特征表达与国外相关研究十分吻合,并且首次获得L.D—His和L.D—Trp4种氨基酸的结构信息。结论:本组研究设立HMR分析条件:脉宽PW=5.8,增益RG=26,驰豫=0.2.采样NS=36,谱宽SW=4000Hz,偏置01=3800条。实验证明能满足分析需要。
基金supported by the National Natural Science Foundation of China (20601023 and 20871102)Zhejiang Provincial Natural Science Foundation (R407087)the Fundamental Research Funds for the Central Universities and Daming Biomineralization Foundation
文摘The formation of dipeptides from amino acids can be driven by hydroxyapatite at a relatively low temperature in air. For example, the formation of (Ala)2 from Ala is induced on hydroxyapatite at 110°C with considerable yield. Typically, condensing agents, high temperatures (>250°C) or high pressures (>25 MPa) are required to drive the condensation of amino acids. Similar effects are observed in the condensation of Gly, Glu and Asp. Experiments demonstrate that hydroxyapatite is an effective inorganic catalytic agent, reducing the activation barrier for the formation of dipeptides by more than 50%. HAP promotes condensation by adsorbing amino acid monomers in an organized manner, which decreases the distance between amino and carboxyl groups on neighboring molecules and extends the contact time of the reaction groups. This work provides a chemical understanding of the primitive condensation of amino acids and reveals a mechanism for enhancement of mineral catalysts. It is important that the conditions used for hydroxyapatite-assisted dipeptide formation are not harsh and can be readily achieved, revealing a possible mechanism for the chemical evolution of biomolecules over geologic ages.
文摘The detection of single amino-acid variants （SAVs） usually depends on single-nucleotide polymorphisms （SNPs） database. Here, we describe a novel method that discovers SAVs at proteome level independent of SNPs data. Using mass spectrometry-based de novo sequencing algorithm, peptide-candidates are identified and compared with theoretical protein database to generate SAVs under pairing strategy, which is followed by database re-searching to control false discovery rate. in human brain tissues, we can confidently identify known and novel protein variants with diverse origins. Combined with DNA/RNA sequencing, we verify SAVs derived from DNA mutations, RNA alternative splicing, and unknown post-transcriptional mechanisms. Furthermore, quantitative analysis in human brain tissues reveals several tissue-specific differential expressions of SAVs. This approach provides a novel access to high-throughput detection of protein variants, which may offer the potential for clinical biomarker discovery and mechanistic research.
