Quantitative Proteomics Services To Upgrade Your Research
Whitepaper
Published: August 11, 2023
Proteomics provides crucial insights into cell signaling and disease mechanisms for biomedical and clinical research. Nevertheless, traditional LC-MS/MS methods have limitations in sensitivity, reproducibility and scalability within proteomics applications.
Recent years have seen the emergence of new technologies aimed at overcoming these challenges. Notably, a new generation of 4D data independent acquisition (DIA) mass spectrometry technology now adds ion mobility as a fourth separation component to expertly sidestep data imbalance arising from randomness.
Recent years have seen the emergence of new technologies aimed at overcoming these challenges. Notably, a new generation of 4D data independent acquisition (DIA) mass spectrometry technology now adds ion mobility as a fourth separation component to expertly sidestep data imbalance arising from randomness.
Download this factsheet to discover:
- The principles and advantages of 4D-DIA quantitative proteomics and 4D phosphoproteomics
- How 4D phosphoproteomics can overcome the challenge of phosphorylation isomerization for site identification
- Methods that can improve detection accuracy and reduce spectra complexity
FACTSHEET
4D-DIA Quantitative Proteomics and 4D Phosphoproteomics
Next Generation Ion Mobility
Mass Spectrometry-based
Proteomics Services
2
Next Generation Ion Mobility Mass Spectrometry-based
Proteomics Services Overview
Crown Bioscience, in partnership with leading third-party
proteomics providers, offers next generation ion mobility-mass
spectrometry (IM-MS)-based-proteomics services to global
clients.
This will allow clients to assess the biological function of proteins
for understanding signalling mechanisms within cells as well
as specific biomarkers to diseases, and systematically assess
quantitative differences in protein profiles of distinct samples for
biomedical and clinical research.
Services Offered
• 4D-DIA quantitative proteomics
• 4D phosphoproteomics
• Bundle package (4D-DIA Proteomics + 4D Phosphoproteomics)
Applications
• Global proteomics profiling of cells or tissues, with/without
treatment
• Proteomics biomarker discovery and validation
• Drug mechanism of action and toxicity studies
• Disease mechanism studies
• Target identification and validation
• Complementary analysis and correlation approaches for other
omics analysis
Our Advantages
• Better reproducibility: no missing values, reduced batch effect,
better data parallelism, and traceability
• Increased sensitivity, wider dynamic range, and improved
detection depth: identify more proteins from same or lower
amount of sample, significantly improved quantification
especially for low abundant proteins
• Lower amount of samples required
• Suitable for large sample cohort studies
• Customized bioinformatic analysis available for large cohort
studies
Factors to Consider When Choosing Mass Spectrometry-based
Proteomics Services
Liquid chromatography (LC) coupled with MS has become the
gold standard in various omics fields. When choosing proteomics
services, there are several factors to consider:
• Data completeness and reproducibility
• Sensitivity and identification depth:
• Number of identified and quantified proteins
• Low abundant protein identification and quantification
• Sample amount requirement
• Speed, throughput, robustness and cost
• Data analysis
4D-DIA Quantitative Proteomics: A Combination of 4D
Proteomics and DIA Technology
A new generation of 4D-DIA proteomics technology (Figure 1)
combines 4D proteomics, which added ion mobility as the fourth
separation dimension to traditional LC-MS/MS (retention time,
mass-to-charge ratio (m/z) and MS/MS fingerprint), with
data independent acquisition (DIA) strategy, which avoids
data imbalance caused by randomness by realizing "lossless
acquisition" of all possible data.
+
Higher sensitivity
Deeper protein
identification
Better data
reproducibility
More reliable
quantification
Smaller sample
size required
4D
proteomics
DIA
4D-DIA
proteomics
Figure 1: 4D-DIA proteomics
3
DDA-MS
MS1 MS2
Survey scan &
precursor selection
m/z
m/z
Intensity
Intensity
Intensity
DIA-MS
Survey scan &
across all isolation windows
Fragmentation of
selected precursors
Fragmentation of
all precursors in each window
m/z
Intensity
m/z
Cutting-edge 4D Proteomics Technology
Classic LC-MS/MS-based bottom-up proteomics separate
peptides based on 3 dimensions: chromatographic retention
time (RT); m/z and ion intensity.
Ion mobility analysis is a gas-phase technique allowing the
separation of ions based on their mobility through an inert
gas (typically helium or nitrogen) under the influence of an
electric field. Adding ion mobility as an additional dimension
of separation for peptide ions to LC-MS/MS analysis has
become increasingly popular for proteomics studies
(Figure 2). It significantly improves the scanning speed and
detection sensitivity, as well as enhances proteomic analysis
performance in terms of identification depth, detection cycle,
and quantitative accuracy.
3
2
1
4
300 400 500 600 700 800 900 1000 1100 1200 m/z
0.7
BPC 400.0000-1000.0000 + Al MS FullScan
0.8
1
1.1
1.2
1.3
1.4
1.5
0.9
Intens.
x10⁶
2.0
1.5
1.0
0.5
0.0 0 10 20 30 40 50 60 70 80 90 100 Time [min]
4D Proteomics
1 — Retention time 2 — Mass-to-charge ratio (m/z)
3 — Intensity 4 — Ion mobility
Data Dependent / Independent Acquisition (DDA / DIA)
There are two data acquisition strategies in tandem mass
spectrometry (MS/MS) data acquisition (Figure 3):
DDA mode: The mass spectrometer selects a fixed number
of most intense precursor ions. They are then fragmented and
analyzed, in the second stage of tandem mass spectrometry.
DIA mode: The mass spectrometer divides the full scan range of
mass spectrometry into several windows and selects, fragments,
and collects all ions in each window.
DIA strategy avoids data imbalance caused by randomness by
realizing "lossless acquisition" of all possible data. However, the
"all-acquisition" strategy produces a highly complex spectrogram
that poses a great challenge to data analysis.
Figure 2: 4D proteomics Figure 3: DDA and DIA data acquisition
4
Technical Strengths of 4D-DIA Quantitative Proteomics
4D Alignment for Better Identification
The greatest challenge in traditional DIA without ion mobility
separation lies in the difficulty of reliably analyzing mixed
spectra. During quantification, matching is mainly based on
chromatographic elution time (retention time). However, due
to co-elution, the retention time alone is not enough, and many
other interfering signals will affect the detection accuracy.
4D technology provides ion-mobility separation and adds an
extra dimension for calibration. It can accurately discriminate the
specific peptide signals from the mixed spectra of DIA, effectively
reducing spectra complexity and improving the detection
accuracy and reliability of DIA (Figure 4).
Nearly 100% Ion Utilization, Maximized Detection Sensitivity
In the 4D-diaPASEF scanning mode, the ion-mobility-related CCS
value correlates well with m/z. This feature allows the Quadrupole
to scan gradually to collect nearly 100% of the ion signals, greatly
enhancing the sensitivity and depth of detection (Figure 5).
In comparison, in the traditional LC-MS/MS-based proteomics
without ion mobility separation, only limited signals can be
collected.
Significant Improvement in Detection Depth
4D-DIA identifies and quantifies low-abundant proteins more
accurately than traditional methods, thereby increasing the depth
of proteomics detection (Figure 6).
Better quantitative integrity
4D-DIA technology can further push the limits of sensitivity with
advanced instrument performance and upgraded acquisition
methods. Even at this trace level, 4D-DIA showed 85% data
integrity for protein quantification (Figure 7).
Figure 4: The chromatograms of EVGSHFDDFVTNLIEK
peptide after calibration in traditional DIA (top) and
4D-DIA (bottom). There is a high interference signal
in the traditional DIA method (top), while the signal
background in the 4D-DIA (bottom) is much cleaner.
Figure 6: >7,500 proteins can be identified
from a single injection of 200 ng of HeLa lysate
(120-minute run time), and 6,974 proteins can
be quantified with 96% data completeness in
triplicate runs. In comparison, conventional
proteomics usually requires μg-level samples to
detect about 5,000 proteins.
Figure 7: >3,000 protein can be identified
from a single injection of 10 ng HeLa lysate
(120-minute run time), and 3,323 proteins can
be identified by triplicated runs. While under
the same study conditions, the 4D-DDA mode
could only identify 2,723 proteins.
Replicate Replicate
200 ng HeLa lysate 10 ng HeLa lysate
Figure 5: 4D-DIA based on the 4D platform can reach nearly 100% ion utilization. Left–Data acquisition in 4D-DIA mode;
Right–Comparison of ion utilization among 4D-DIA, DDA, and DIA. (Source: Florian Meier, et al. Nature Methods.)
4D-DIA Technology Effectively Reduces the
Complexity of the Spectrum
600 2000 y11-1340.6733*
y10-1193.6048*
500
1500
1000
500
1600
400
300
Intensity (10*3)
Intensity
200
100
0
68.8 71.6 71.7 71.8 71.9 72.0 72.1 72.2 69.0 69.2
Retention Time Retention Time
69.4 69.6 69.8
y3-389.2395*
y12-739.3697**
69.3
+1 ppm
12 9
b9-1034.4214*
y7-816.4825+
y6-717.4141+
y4-502.3235+
b8-887.3530+
b10-1133.4896* b9-1034.4214+
71.8
-2.6 ppm
69.8
-10.1 ppm
2000 340.6733*
93.6048*
1500
1000
500
1600
Intensity
71.6 71.7 71.8 71.9 72.0 72.1 72.2 Retention Time
69.8
9.2395*
39.3697**
9
34.4214*
y7-816.4825+
y6-717.4141+
y4-502.3235+
b8-887.3530+
133.4896* b9-1034.4214+
71.8
-2.6 ppm
69.8
-10.1 ppm
MS1
Fragmentation
m/z
MS2
m/z
Ion Mobility 1/K0
diaPASEF scan
1.5
DDA
1.0
Aligned Retention Time (min)
Abundance x 10⁴ (a.u.) 0.5
16.5
0.0
16.6 16.7
DIA
diaPASEF
1 2 3 Total
8,000
7,000
Proteins
6,000
5,000
4,000
3,000
2,000
1,000
0
1 2 3 Total
3,500
3,000
Proteins2,500
2,000
1,500
1,000
500
0
5
Isomerization Brings Site Identification Challenge for
Phosphoproteomics
Phosphorylation is a common type of post translational
modifications (PTM), with more than 30% of proteins in cells
phosphorylated. Phosphorylation is the process of transferring
phosphate groups from ATP or GTP to specific sites (usually
Ser, Tyr, Thr) of proteins, catalyzed by phosphorylating kinase
(Figure 8). It is one of the most fundamental, prevalent, and
important mechanisms to regulate and control protein activity
and function, and is involved in various physiological and
pathological processes, regulating cellular activities such as
proliferation, development, differentiation, and apoptosis.
Phosphorylation on different sites on the same peptide can lead
to phosphopeptide isomers co-elution on chromatography
(Figure 9). These co-eluted phosphopeptide isomers cannot
be separated on conventional LC-MS/MS platforms. According
to available statistics, at least 26% of phosphopeptides have
isomers, 50% of which cannot be effectively differentiated on
chromatography, making it difficult to identify phosphorylation
sites.
Signal input
Signal output
Enzyme
State ‘B’
PTM crosstalk
Localization Activity
Conformation Binding
Turnover
State ‘A’
Enzyme
P
P
PP
ATP P
ADP
P P
P
P
Kinase
Me P Ub Ac
P P
Histogram Phosphopeptide Positional Isomer
RT Difference
B Co-elute
fragment
B Co-elute
ferential
gmentation
B Co-elute
onclusive
gmentation
Bferential RT
60%
50%
8% 6% 6% 4% 3% 3% 3% 3% 2% 2% 1% 1% 1% 1% 1% 1% 1% 1% 2%
50%
Retention Time Difference Between Positional Isomers (min)
Percentage of Isomer Pairs 40%
30%
20%
10%
0%
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
2.5
2.75
3
3.25
3.5
3.75
4
4.25
4.5
4.75
5
5.25
5.5
5.75
6
6.25
6.5
6.75
7
7.25
7.5
7.75
8
>8
Phosphopeptide
Positional
Isomers
Figure 8: Phosphorylation
Figure 9: Isomerization brings site identification challenge for phosphoproteomics
6
4D Phosphoproteomics
Features
• Immobilized metal affinity chromatography (IMAC)
strategy: using proprietary targeted antibodies to enrich
phosphopeptides, to reduce sample complexity
• Additional ion mobility separation enables more reliable and
deeper coverage for phosphorylation
• Strict dual quality control to remove low confident data: false
discovery rate (FDR, 1%); false localization rate (FLR, 0.75)
• Upgraded bioinformatic analysis available: kinase prediction,
signaling analysis, and data mining
Technical Strengths of 4D Phosphoproteomics
Deeper Coverage of Phosphorylation Site Identification
4D technology brings a dramatic increase in detection depth and
sensitivity. The timsTOF Pro system can acquire up to 100 MS/MS
spectra per 1.1 second scanning cycle.
>10,000 phosphorylation sites (localization probability > 0.75) were
identified with high confidence in various cell tissues, 50% higher
than the traditional method (Figure 10).
More Reliable Modification Identification Results
4D phosphoproteomics resolves the issue of isomerization in
PTM through ion mobility separation, which ensures more reliable
identification of PTMs.
As shown in Figure 11, the elution time and m/z ratio of many
phosphorylated peptide isomers are identical, but the structural
differences of the phosphorylation locations can be effectively
detected by ion mobility.
The separation of both ion mobility and HPLC can maximize the
identification and differentiation of these co-eluted modified
peptide signals.
Protein extraction
and enzymolysis
Enrichment of
phosphorylated
peptides
Pre-separation LC-MS/MS Site identification
and quantification
Phosphoproteomic
data mining
4D Phosphoproteomics Quantitative Analysis Workflow
Figure 10: Deep coverage of phosphorylation Figure 11: Adding ion mobility as the 4th separation dimension help to identify co-eluted modified peptides
site identification
0.0 0.2 0.4
Localization Probability
Confidence
0.6 0.8 1.0
25
0.75
FLR threshold
=0.75
Low High
# Phosphorylation Sites (x1000)
20
15
10
5
0
Human
Stomach
Tissue
Mouse
Brain
Tissue
HeLa 293T
18000
16000
Phosphosites 14000
12000
10000
8000
6000
4000
2000
0
0.0 0.2 0.4
Localization Probability
Confidence
0.6 0.8 1.0
25
0.75
FLR threshold
=0.75
Low High
# Phosphorylation Sites (x1000)
20
15
10
5
0
Mouse
Brain
issue
HeLa 293T
Mass Spectrometry Core Facility
• Top mass spectrometers such as Bruker timsTOF Pro/ timsTOF
Pro 2 series, and Thermo Fisher Scientific Orbitrap Exploris™ 480
• Additional separation dimension by ion mobility separation to
traditional LC-MS/MS based proteomics
• Bruker Trapped Ion Mobility Spectrometry (TIMS)
• Thermo Fisher Scientific FAIMS
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Get in touch
Science
busdev@crownbio.com consultation@crownbio.com
www.crownbio.com
• Unique diaPASEF technology to dramatically increase data
acquisition speed
• Evosep One provides robust and excellent chromatographic
separation
• Continuous analysis of thousands of samples to provide stable
performance without cleaning, enhancing the stability of batch
analysis
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