6 research outputs found
Hydrophobic Tagging-Assisted N‑Termini Enrichment for In-Depth N‑Terminome Analysis
The analysis of protein
N-termini is of great importance for understanding
the protein function and elucidating the proteolytic processing. Herein,
we develop a negative enrichment strategy, termed as hydrophobic tagging-assisted
N-termini enrichment (HYTANE) to achieve a global N-terminome analysis.
The HYTANE strategy showed a high efficiency in hydrophobic tagging
and C18 material-assisted depletion using bovine serum albumin (BSA)
as the sample. This strategy was applied to N-termini profiling from <i>S. cerevisiae</i> cell lysates and enabled the identification
of 1096 protein N-termini, representing the largest N-terminome data
set of <i>S. cerevisiae</i>. The identified N-terminal
peptides accounted for 99% of all identified peptides, and no deficiency
in acidic, histidine (His)-containing, and His-free N-terminal peptides
was observed. The presented HYTANE strategy is therefore a highly
selective, efficient, and unbiased strategy for the large scale N-terminome
analysis. Furthermore, using the HYTANE strategy, we identified 329
cleavage sites and 291 substrates of caspases in Jurkat cells, demonstrating
the great promise of HYTANE strategy for protease research. Data are
available via ProteomeXchange with identifier PXD004690
Enzymatic Reactor with Trypsin Immobilized on Graphene Oxide Modified Polymer Microspheres To Achieve Automated Proteome Quantification
Protein
digestion and isotope labeling are two critical steps in
proteome quantification. However, the conventional in-solution protocol
unavoidably suffers from disadvantages such as time-consuming, low
labeling efficiency, and tedious off-line manual operation, which
might affect the quantification accuracy, reproducibility, and throughput.
To address these problems, we developed a fully automated proteome
quantification platform, in which an ultraperformance immobilized
microreactor (upIMER) with graphene-oxide-modified polymer microspheres
as the matrix was developed, to achieve not only the simultaneous
protein digestion and <sup>18</sup>O labeling, but also the online
integration with nano-high-pressure liquid chromatography–electrospray
ionization-tandem mass spectrometry (nanoHPLC–ESI-MS/MS). Compared
to the conventional off-line protocols, such a platform exhibits obviously
improved digestion and <sup>18</sup>O labeling efficiency (only 8%
peptides with missed cleavage sites, 99% labeling efficiency, and
2.5 min reaction time), leading to the increased quantification coverage,
accuracy, precision and throughput. All the results demonstrated that
our developed fully automated platform should provide new opportunities
to improve the accuracy, reproducibility, and throughput for proteome
quantification
Gold-Coated Nanoelectrospray Emitters Fabricated by Gravity-Assisted Etching Self-Termination and Electroless Deposition
To improve the stability
and sensitivity of nanoelectrospray for
liquid chromatography-mass spectroscopy (LC-MS) analysis, we present
a new method to fabricate gold-coated emitters. Via gravity-assisted
etching self-termination, the emitter with a tapered outer surface
and a straight inner surface is prepared with good reproducibility,
without the need of fluid introduced to protect internal surface during
etching. Followed by electroless deposition, the emitter is further
coated with gold film homogeneously, by which the relative standard
deviation (RSD) value of total ion current in 160 h is <5%, showing
good stability. Compared to that obtained by a commercial emitter,
the identified protein number from 2 μg HeLa cell digests is
increased over 10%, contributed by the stable electrospray and improved
signal intensity of peptides. Furthermore, the integrated gold-coated
emitter is prepared at the end of the ultranarrow-bore packed column
(inner diameter of 25 μm), and 218 proteins are identified from
2 ng HeLa cell digests. All of these results demonstrate the great
promise of such emitters for use in ultrasensitive proteome analysis
In-Depth Proteomic Quantification of Cell Secretome in Serum-Containing Conditioned Medium
Secreted proteins play key roles
during cellular communication,
proliferation, and migration. The comprehensive profiling of secreted
proteins in serum-containing culture media is technically challenging.
Most studies have been performed under serum-free conditions. However,
these conditions might alter the status of the cells. Herein, we describe
an efficient strategy that avoids the disturbance of serum by combining
metabolic labeling, protein “equalization,” protein
fractionation, and filter-aided sample preparation, called MLEFF,
enabling the identification of 534 secreted proteins from HeLa conditioned
media, including 31 cytokines, and growth factors. This MLEFF strategy
was also successfully applied during a comparative secretome analysis
of two human hepatocellular carcinoma cell lines with differentially
metastatic potentials, enabling the quantification of 61 significantly
changed proteins involved in tumor invasion and metastasis
In-Depth Proteomic Quantification of Cell Secretome in Serum-Containing Conditioned Medium
Secreted proteins play key roles
during cellular communication,
proliferation, and migration. The comprehensive profiling of secreted
proteins in serum-containing culture media is technically challenging.
Most studies have been performed under serum-free conditions. However,
these conditions might alter the status of the cells. Herein, we describe
an efficient strategy that avoids the disturbance of serum by combining
metabolic labeling, protein “equalization,” protein
fractionation, and filter-aided sample preparation, called MLEFF,
enabling the identification of 534 secreted proteins from HeLa conditioned
media, including 31 cytokines, and growth factors. This MLEFF strategy
was also successfully applied during a comparative secretome analysis
of two human hepatocellular carcinoma cell lines with differentially
metastatic potentials, enabling the quantification of 61 significantly
changed proteins involved in tumor invasion and metastasis
3‑Carboxybenzoboroxole Functionalized Polyethylenimine Modified Magnetic Graphene Oxide Nanocomposites for Human Plasma Glycoproteins Enrichment under Physiological Conditions
Boronate
affinity materials have been successfully used for the
selective recognition of glycoproteins. However, by such materials,
the large-scale glycoproteins enrichment from human plasma under physiological
conditions is rarely reported. In this work, 3-carboxybenzoboroxole
(CBX) functionalized polyethylenimine (PEI) modified magnetic graphene
oxide nanocomposites were synthesized. Benefitting from the low p<i>K</i><sub>a</sub> value of CBX (∼6.9) and PEI dendrimer-assisted
multivalent binding, the Freundlich constant (<i>K</i><sub>F</sub>) for the adsorption of horseradish peroxidase (HRP) was 3.0–7.3
times higher than that obtained by previous work, displaying the high
enrichment capacity. Moreover, PEI could improve the hydrophilicity
of nanocomposites and reduce nonglycoprotein adsorption. Therefore,
such nanocomposites were successfully applied to the analysis of human
plasma glycoproteome under physiological conditions, and the identified
glycoproteins number and recognition selectivity was increased when
compared to the results obtained by previous boronic acid-functionalized
particles (Sil@Poly(APBA-<i>co</i>-MBAAm)) under common
alkaline condition (137 vs 78 and 67.8% vs 57.8%, respectively). In
addition, thrombin (F2), an important plasma glycoprotein, labile
under alkaline conditions, was specifically identified by our method,
demonstrating the great promise of such nanocomposites in the deep-coverage
glycoproteome analysis