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A Quasi-direct LC-MS/MS-based Targeted Proteomics Approach for miRNA Quantification via a Covalently Immobilized DNA-peptide Probe

Author：Liang Liu, Qingqing Xu, Shuai Hao & Yun Chen   《Scientific Reports》

ABSTRACTS
MicroRNAs (miRNAs) play a vital role in regulating gene expression and are associated with a variety of cancers, including breast cancer. Their distorted and unique expression is a potential marker in clinical diagnoses and prognoses. Thus, accurate determination of miRNA expression levels is a prerequisite for their applications. However, the assays currently available for miRNA detection typically require pre-enrichment, amplification and labeling steps, and most of the assays are only semi-quantitative. Therefore, we developed a quasi-direct liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based targeted proteomics approach to quantify target miRNA by innovatively converting the miRNA signal into the mass response of a reporter peptide via a covalently immobilized DNA-peptide probe. Specifically, the probe containing the targeted proteomics-selected substrate/reporter peptide, GDRAVQLGVDPFR/AVQLGVDPFR, and the DNA sequence complementary to the target miRNA (i.e., miR-21) was first immobilized on APMTS modified silica nanoparticles using PDITC. After the immobilized probe was recognized and hybridized with the target miRNA, the excess probe was degraded using MBN and followed by a trypsin digestion of the hybrids. The reporter peptide was released and quantified using LC-MS/MS. The obtained LOQ was 5 pM. Finally, the developed assay was used for the quantitative analysis of miR-21 in breast cells and tissue samples.
SCREENSHOT

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Maleimidohexanoic acid-modified substrate peptide (Male- GDRAVQLGVDPF -R), reporter peptide (AVQLGVDPFR) as well as internal standard peptide containing stable-isotope labeled amino acids were synthesize by ChinaPeptides Co., Ltd
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https://www.nature.com/articles/s41598-017-05495-7
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CAS:85466-18-8|Thymopoietin II (32-35)|RKDV

Contact： Liven Qian(钱叶华)-Custom Peptide Mobile: 13761298676（微信） Email：cps037@chinapeptides.net QQ：2880526724 ChinaPeptides Co., Ltd./强耀生物科技有限公司 Name Thymopoietin II (32-35) Code [85466-18-8] The alias Thymopoietin II (32-35) Sequence (single letter abbreviation) RKDV Sequence (three-letter abbreviation) H-Arg-Lys-Asp-Val-OH (trifluoroacetate salt) A basic description TP-4 and TP-3; shortest active thymopoietin II fragments described that exhibit potent immunoregulatory properties in vitro and in vivo. solubility The molecular weight 516.6 Chemical formula C21H40N8O7 The purity 80%，90%，95%，98%，99% Weight 1mg,5mg,10mg,50mg,100mg,1g Storage conditions Store at -20°C. Keep tightly closed. Store in a cool dry place. Number of Residues: 4 1-Letter Code: RKDV 3-Letter Code: Arg-Lys-Asp-Val Molecular weight (Mr): 516.6 g/mol Isoelectric point: 10.1 Net charge at pH 7.0: 1.0 Average hydrophilicity: 1.9 Ratio of hydrophilic residues / total number of residues...
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