- Protein quantitative labeling reagent and preparation method and application thereof
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The invention provides a protein quantitative labeling reagent as well as a preparation method and application thereof. According to the protein quantitative labeling reagent provided by the invention, the high reaction activity of a o-phthalaldehyde grou
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Paragraph 0052; 0055; 0071-0072
(2020/04/17)
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- Novel isotopic N,N-Dimethyl Leucine (iDiLeu) reagents enable absolute quantification of peptides and proteins using a standard curve approach
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Absolute quantification of protein targets using liquid chromatography-mass spectrometry (LC-MS) is a key component of candidate biomarker validation. One popular method combines multiple reaction monitoring (MRM) using a triple quadrupole instrument with stable isotope-labeled standards (SIS) for absolute quantification (AQUA). LC-MRM AQUA assays are sensitive and specific, but they are also expensive because of the cost of synthesizing stable isotope peptide standards. While the chemical modification approach using mass differential tags for relative and absolute quantification (mTRAQ) represents a more economical approach when quantifying large numbers of peptides, these reagents are costly and still suffer from lower throughput because only two concentration values per peptide can be obtained in a single LC-MS run. Here, we have developed and applied a set of five novel mass difference reagents, isotopic N,N-dimethyl leucine (iDiLeu). These labels contain an amine reactive group, triazine ester, are cost effective because of their synthetic simplicity, and have increased throughput compared with previous LC-MS quantification methods by allowing construction of a four-point standard curve in one run. iDiLeu-labeled peptides show remarkably similar retention time shifts, slightly lower energy thresholds for higher-energy collisional dissociation (HCD) fragmentation, and high quantification accuracy for trypsin-digested protein samples (median errors 15%). By spiking in an iDiLeu-labeled neuropeptide, allatostatin, into mouse urine matrix, two quantification methods are validated. The first uses one labeled peptide as an internal standard to normalize labeled peptide peak areas across runs (19% error), whereas the second enables standard curve creation and analyte quantification in one run (8% error).
- Greer, Tyler,Lietz, Christopher B.,Xiang, Feng,Li, Lingjun
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p. 107 - 119
(2015/02/19)
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- N,N-Dimethyl leucines as novel Isobaric tandem mass tags for quantitative proteomics and peptidomics
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Herein, we describe the development and application of a set of novel N,N-dimethyl leucine (DiLeu) 4-plex isobaric tandem mass (MS2) tagging reagents with high quantitation efficacy and greatly reduced cost for neuropeptide and protein analysis. DiLeu reagents serve as attractive alternatives for isobaric tags for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency, and improved fragmentation efficiency. DiLeu reagent resembles the general structure of a tandem mass tag in that it contains an amine reactive group (triazine ester) targeting the N-terminus and ε-amino group of the lysine side chain of a peptide, a balance group, and a reporter group. A mass shift of 145.1 Da is observed for each incorporated label. Intense a1 reporter ions at m/z 115.1, 116.1, 117.1, and 118.1 are observed for all pooled samples upon MS2. All labeling reagents are readily synthesized from commercially available chemicals with greatly reduced cost Labels 117 and 118 can be synthesized in one step and labels 115 and 116 can be synthesized in two steps. Both DiLeu and iTRAQ reagents show comparable protein sequence coverage (~43%) and quantitation accuracy ( a marine model organism, Callinectes sapidus.
- Xiang, Feng,Ye, Hui,Chen, Ruibing,Fu, Qiang,Li, Ngjun
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experimental part
p. 2817 - 2825
(2010/08/22)
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- STABLE ISOTOPE-LABELED AMINO ACID, METHOD OF INTEGRATING THE SAME INTO TARGET PROTEIN, METHOD OF NMR STRUCTURAL ANALYSIS OF PROTEIN AND PROCESS FOR PRODUCING SITE-SELECTIVE STABLE ISOTOPE-LABELED FUMARIC ACID AND TARTARIC ACID
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The present invention provides a stable isotope-labeled amino acid which is at least one of amino acids constituting a protein and which has at least one of the following labeling patterns:(a) hydrogen atoms except at least one hydrogen atom in one or more methylene groups are deuterated,(b) hydrogen atoms in one of prochiral gem-methyl groups are completely deuterated,(c) hydrogen atoms in prochiral methyl groups are partially deuterated, and(d) all hydrogen atoms except one of them in methyl group are deuterated and hydrogen atoms in the aromatic ring are partially deuterated. With the stable isotope-labeled amino acid, the deuteration of protein can be attained without damaging the NMR sensitivity of remaining hydrogen nucleus and, in addition, the rapid, accurate analysis of NMR spectrum of a high-molecular protein which is beyond the limitation in the prior art and the determination of the stereo-structure can be performed at the same time.
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- Synthesis of L-threo- and L-erythro-amino acids: novel probes for conformational analysis of peptide side chains
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An efficient and convenient route for the preparation of L-threo- and L-erythro-amino acids 5 as probes for the conformational analysis of peptide side chains by NMR spectroscopy is described.Stereoselective incorporation of deuterium into the α,β-positions of amino acid 5 was accomplished by catalytic deuteration of dehydroamino acid derivatives 1 and 2 followed by a combination of enzymic optical resilution and the racemization at the 2-position.Using these doubly labelled amino acids, it was possible to obtain vicinal coupling constants between carbonyl carbon and prochiral β-protons, J(13C-1Hβ1) and J(13C1-1Hβ2), through 13C NMR spectroscopy alone.We also demonstrate the determination of the fractional populations of rotamers in respect of the Cα-Cβ bond of the amino acids using the measured coupling constants.
- Oba, Makoto,Ueno, Ryuichi,Fukuoka, Mika,Kainosho, Masatsune,Nishiyama, Kozaburo
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p. 1603 - 1610
(2007/10/02)
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