Hydrogenation of CO2 into aromatics over a ZnCrO: X-zeolite composite catalyst

Article abstract of DOI:10.1039/c8cc09019j

A ZnCrO_x-ZnZSM-5 composite catalyst was used for CO₂ hydrogenation into hydrocarbons especially aromatics (Aro). 81.1% Aro selectivity in C₅₊ hydrocarbons (mainly C_5-11) was obtained at 320 °C, corresponding to 19.9% CO₂ conversion, 29.8% total hydrocarbons (HC_t) selectivity and 69.7% C₅₊ selectivity in HC_t. Our optimized STY of Aro is the highest ever reported.

Full text of DOI:10.1039/c8cc09019j

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Lectin inspired polymers based on the dipeptide
Ser-Asp for glycopeptide enrichment†
Cite this: Analyst, 2018, 143, 5090
a
B. Zhang,a R. Z. Yu,b Y. H. Yu,a C. Peng,a R. Xie,a Y. Zhanga and J. Y. Chen
*
Received 10th July 2018,
Accepted 8th September 2018
DOI: 10.1039/c8an01258j
rsc.li/analyst
Lectin inspired polymers were prepared through modification of though the single peptide–carbohydrate interaction is weak,
silica microspheres with Ser-Asp (SD). This functional polymer the multiple binding sites form a network and enhance these
showed distinct adsorption and retention towards different disac- interactions. These peptide–carbohydrate interactions inspire
charides and demonstrated high-efficiency enrichment of us to design artificial lectins for glycopeptide enrichment.
glycopeptides.
In this paper, a lectin inspired polymer was prepared
through modification of anino-silica microspheres with poly-
merized Ser-Asp (SD) (denoted as polySD-SiO2 in Fig. 1a). The
Ser-Asp was selected to mimic the amino acid residues in
lectins and the polymer chain is used to amplify the stereo-
The covalent binding of glycans on proteins not only regulates
the important biological processes but also reflects the state of
cells. Typically, enzymes are equipped with certain glycans for
recognition sites in gene transcription or protein trans-
lation.1,2 Aberrant protein glycosylation can change the
physicochemical properties or structures of biomolecules, and
then trigger diseases, e.g., N-glycosylated tau protein can only
be detected in biofluids in Alzheimer’s disease.3 Therefore, it
is important to identify protein glycosylation, which provides
information about the protein sequence, glycosylation sites
and glycan structures. However, it is difficult to characterize
protein glycosylation with state-of-the-art mass spectrometry
(MS) because of the low abundance of glycopeptides.4
In the last decade, several enrichment methods for glyco-
peptides have been developed, including lectin affinity
chromatography,5–7 hydrophilic interaction chromatography,8,9
boronic acid affinity chromatography,10,11 etc. Among these,
lectin affinity chromatography is widely used to enrich glyco-
peptides/glycoproteins.5 Lectin recognizes specific carbo-
hydrate moieties through the reversible binding between the
anomeric hydroxyl groups on carbohydrates and the hydro-
philic groups from amino acid residues in lectin protein.12,13
Such interactions are interpreted as the synergistic effects of
multiple forces, including hydrogen bonding, CH–π inter-
actions, ion pairing, van der Waals forces, etc.14,15 Even
aDepartment of Gastrointestinal Surgery, Union Hospital, Tongji Medical College,
Huazhong University of Science and Technology, Wuhan 430022, China.
E-mail: union.bzhang@aliyun.com
bMedical Department, Chinese People’s Liberation Army 210 Hospital, Dalian,
Liaoning 116015, China
Fig. 1 The synthesized materials were characterized by X-ray photo-
electron spectroscopy (a), scanning electron microscopy (silica before
(c) and after modification (d), thermogravimetry analysis (e) and zeta
potential analysis (f).
†Electronic supplementary information (ESI) available. See DOI: 10.1039/
c8an01258j
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Fig. 2 Separation of disaccharides (a) and fructo-saccharides (b) with a
polySD-SiO2 packed column and the samples were detected with an
evaporative light scattering detector (ELSD). The flow rate was 1.0 mL
min−1 and the column temperature was 30 °C. The mobile phase A:
100% CH3CN, the mobile phase B: 100% H2O. Gradient for the separ-
ation of disaccharides: 0–12 min, 80%–65% A; gradient for the separ-
ation of fruto-oligosaccharides: 0–12 min, 80%–65% A; 12–27 min,
65%–55% A. ELSD conditions: Gas pressure 30 psi, tube temperature
70 °C, gain 10.
Scheme 1 The synthesis route of polySD-SiO2.
selective recognition between Ser-Asp and glycans. The bio-
inspired material polySD-SiO2 was synthesized by surface
initiated atom transfer radical polymerization (Scheme 1)
because this method is robust and easy to prepare, and uses polymerization degrees, as labelled by numbers (Fig. 2b). The
commercially available, inexpensive catalysts and initiators.16–19
fructo-oligosaccharides with low to high polymerization
The synthesized materials were characterized by high degrees could be gradually eluted from the adsorbent using a
resolution scanning electron microscopy (HRSEM), zeta poten- solution with high to low acetonitrile content, which matches
tial analysis and thermogravimetry analysis (TGA), and used to well with the typical characteristics of hydrophilic interaction
enrich glycopeptides from different samples. HRSEM images chromatography. These data clearly demonstrate the powerful
reveal that polySD-SiO2 materials preserve a similar mor- discrimination capacities of the polySD-SiO2-based column
phology to that of silica microspheres. These data proved that toward different saccharides. This column effectively addresses
polySD-SiO2 materials are not degraded after coating with poly- the problem of saccharide separation and can be widely
mers on the silica surface. The nitrogen sorption isotherm of applied in carbohydrate chemistry.
polySD-SiO2 showed a typical type IV curve (Fig. S1†). The
The enrichment conditions were optimized. The loading
Barrett–Joyner–Halenda (BJH) pore size of polySD-SiO2 was solution was 80% CH3CN/0.1% FA because most of the non-
26 nm compared with 33 nm of silica microspheres without glycopeptides and all glycopeptides retained well under these
modification (Fig. 1b), indicating a 3.5 nm polymer coated on conditions (Fig. S2†). The elution solution was 40% CH3CN/
the silica sphere. The elemental analysis and X-ray photo- H2O/5 mM NH4HCO3 because of the weaker retention of glyco-
electron spectroscopy data (Fig. 1a) imply the presence of peptides at pH 8.0 and a lower CH3CN content (Fig. S3†).
carbon, nitrogen and oxygen on the polySD-SiO2. TGA analysis Tryptic digests of bovine fetuin were chosen as the model
was used to further measure the relative composition of sample, attributing to its definite glycosylation sites and
polySD-SiO2 (Fig. 1e). The sharp decline above 400 °C resulted glycan structures. In order to mimic the complexity of the bio-
from the weight loss of the polymer layer. The zeta-potentials samples, the tryptic digests of bovine fetuin and bovine serum
of polySD-SiO2 under different pH conditions were measured. albumin were mixed at different molar ratios and treated with
As shown in Fig. 1f, the surface charge of polySD-SiO2 is zero polySD-SiO2. After enrichment with polySD-SiO2, up to 43 glyco-
at solution pH 5.1, and negative at a pH higher than 5.1. The peptides were detected from the mixture of fetuin and BSA at a
tunable surface charges are ascribed to the naturally smart molar ratio of 1 : 100, in sharp contrast to no detectable glyco-
zwitterions of Ser-Asp chemical composition. These results peptides in the mixture before enrichment (Fig. S4†). For com-
suggest that polySD-SiO2 was successfully modified on the parison, only 7 glycopeptides were captured from the same
silica microspheres.
sample by commercial zwitterionic hydrophilic interaction
In order to exhibit the distinct discrimination of liquid chromatography (ZIC-HILIC) (Fig. 3c). Moreover, the
polySD-SiO2 toward saccharides, the chromatographic separ- selectivity of the material toward glycopeptides remained even
ation of disaccharides and fructo-oligosaccharides was carried in the case of fetuin and BSA at a molar ratio of 1 : 3000
out. Because of the subtle differences in stereochemistry, (Fig. 3b). It should be noted that some glycopeptides enriched
chemoselective discrimination of disaccharides is very challen- with polySD-SiO2 originated from the impurities of BSA, as
ging. Five disaccharides (sucrose, maltose, leucrose, melibiose, reported in the literature,9 indicating the ability of polySD-SiO2
and gentiobiose) with subtle differences in structure could be to enrich trace glycopeptides from a vast amount of interfer-
well separated with the column (Fig. 2a). The application of ents. These results demonstrate the high selectivity of
this column to oligosaccharides with different polymerization polySD-SiO2 for glycopeptides. The high selectivity of
degrees was also investigated. The components of fructo-oligo- polySD-SiO2 toward glycopeptides might be attributed to the
saccharides were separated into 26 constituents with different reason that the monomer Ser-Asp binds glycans via hydrogen
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Fig. 4 Enriched glycopeptides from tryptic digests of bovine fetuin and
bovine serum albumin (BSA) at a molar ratio of 1 : 100 treated with com-
mercial ZIC-HILIC (a), at molar ratio 1 : 1000 (b) and 1 : 3000 (c) treated
with polySD-SiO2. Glycopeptides are labelled with glycans or red
asterisks.
The established enrichment strategy was further applied to
enrich glycopeptides from the HeLa S3 cell lysate. Three tech-
nical replicates were performed using 20 μg of total protein.
With a false discovery rate of 1% at both the peptide and site
levels, 175, 151, and 165 unique glycosylation sites were
characterized after treatment with polySD-SiO2, respectively
(Fig. 4a). Furthermore, substantial overlap of the identified gly-
cosylation sites could be found between two replicates (Fig S5
in the ESI†). The average selectivity of polySD-SiO2 toward gly-
copeptides was 68% for three technique replicates. The
detailed information of the identified glycosylation sites is
shown in Table S1.† For comparison, Sambucus nigra agglutinin
II (SNA), a lectin, was used to enrich glycopeptides from the
same samples. The numbers of identified glycosylation sites
were 23, 19 and 26, respectively. These numbers are substan-
tially less than those obtained with our materials. This result
could explain that functional monomer Ser-Asp in poly
SD-SiO2 could effectively bind various glycans in the glycopep-
tides, while the SNA is specific to only one subset of glycans.
Gene ontology analysis indicated that 69.6% of the matched
glycoproteins were annotated as binding proteins, and other
glycoprotiens were involved in the cell adhesion and receptor
activity (Fig. 4b). These data exemplify the excellent potential
of our material for use in glycoproteomic analysis.
Fig. 3 The performance of polySD-SiO2 (a and b) and commercial
ZIC-HILIC (c) toward glycopeptides using tryptic digests of bovine fetuin
and bovine serum albumin (BSA) at molar ratios of 1 : 100 (a and c) and
1 : 3000 (b). Glycopeptides are labelled with their corresponding glycans
or red asterisks.
bonds and the multiple sites of Ser-Asp in the polymer further
enhance their interaction.
In addition to its high selectivity toward glycopeptides,
polySD-SiO2 also exhibited high recovery and adsorption
capacity for glycopeptides, which are two important para-
meters to assess adsorbents. A stable-isotope dimethyl label-
ling method20 was performed to determine the recovery of
polySD-SiO2 toward
a
standard glycopeptide (peptide
sequence: KVANKT, N: glycosylation site). The recovery rate was
86.6 5.0% (n = 5), contributing to the strong binding of glyco-
peptides on materials during sample loading and the
Conclusions
thorough elution of targets from materials. The adsorption In conclusion, lectin inspired materials showed high selectivity
capability of polySD-SiO2 toward the standard glycopeptide for glycopeptides, and could enrich low abundance glycopep-
was 83 mg g−1. These results demonstrated the high efficiency tides from both the fetuin/BSA mixture and real biosamples.
of polySD-SiO2 materials for glycopeptide enrichment.
This material could also discriminate disaccharides with a
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slight difference in their structures. These features well match
the demand for fine discrimination of glycans and in-depth
analysis of glycoprotoeomics. As a biomimetic and bioinspired
approach employed in this study, lectin inspired materials
pave the way for designing artificial saccharide receptors with
high specificity.
7 E. Song, R. Zhu, Z. T. Hammond and Y. Mechref,
J. Proteome Res., 2014, 13, 4808–4820.
8 X. Li, Y. Xiong, G. Qing, G. Jiang, X. Li, T. Sun and
X. Liang, ACS Appl. Mater. Interfaces, 2016, 8, 13294–
13302.
9 G. Qing, X. Li, P. Xiong, C. Chen, M. Zhan,
X. Liang and T. Sun, ACS Appl. Mater. Interfaces, 2016, 8,
22084–22092.
Conflicts of interest
10 Z. Bie, Y. Chen, H. Li, R. Wu and Z. Liu, Anal. Chim. Acta,
2014, 834, 1–8.
11 X. Li, H. Liu, G. Qing, S. Wang and X. Liang, J. Mater.
Chem. B, 2014, 2, 2276–2281.
There are no conflicts to declare.
12 Y. Hang, X.-P. He, L. Yang and J. Hua, Biosens. Bioelectron.,
2015, 65, 420–426.
Acknowledgements
13 J. M. Propster, F. Yang, S. Rabbani, B. Ernst, F. H. T. Allain
and M. Schubert, Proc. Natl. Acad. Sci. U. S. A., 2016, 113,
E4170–E4179.
We thank the National Natural Science Foundation of China
(81472487 and 81773197).
14 W. I. Weis, K. Drickamer and W. A. Hendrickson, Nature,
1992, 360, 127–134.
15 W. I. Weis, R. Kahn, R. Fourme, K. Drickamer and
W. A. Hendrickson, Science, 1991, 254, 1608–1615.
16 H. W. Ma, J. H. Hyun, P. Stiller and A. Chilkoti, Adv. Mater.,
2004, 16, 338–341.
Notes and references
1 M. Aebi, R. Bernasconi, S. Clerc and M. Molinari, Trends
Biochem. Sci., 2010, 35, 74–82.
2 R. Kadirvelraj, J.-Y. Yang, J. H. Sanders, L. Liu, A. Ramiah,
P. K. Prabhakar, G.-J. Boons, Z. A. Wood and 17 L. Hua, M. Y. Liu, L. C. Mao, Q. Huang, H. Y. Huang,
K. W. Moremen, Proc. Natl. Acad. Sci. U. S. A., 2018, 115,
4637–4642.
G. J. Zeng, J. W. Tian, Y. Q. Wen, X. Y. Zhang and Y. Wei,
Appl. Surf. Sci., 2018, 434, 204–221.
3 S. A. Yuzwa, A. H. Cheung, M. Okon, L. P. McIntosh and 18 L. Hua, J. Wu, M. Y. Liu, L. C. Mao, H. Y. Huang, Q. Wang,
D. J. Vocadlo, J. Mol. Biol., 2014, 426, 1736–1752.
4 D. F. Zielinska, F. Gnad, J. R. Wisniewski and M. Mann,
Cell, 2010, 141, 897–907.
5 M. Chen, X. Shi, R. M. Duke, C. I. Ruse, N. Dai, C. H. Taron
and J. C. Samuelson, Nat. Commun., 2017, 8, 15487.
Y. F. Dai, Y. Q. Wen, X. Y. Zhang and Y. Wei, J. Colloid
Interface Sci., 2017, 508, 396–404.
19 L. C. Mao, X. H. Liu, M. Y. Liu, L. Hua, D. Z. Xu,
R. M. Jiang, Q. Huang, Y. Q. Wen, X. Y. Zhang and Y. Wei,
Appl. Surf. Sci., 2017, 419, 188–196.
6 E. Ruiz-May, S. Hucko, K. J. Howe, S. Zhang, 20 F. Wang, R. Chen, J. Zhu, D. Sun, C. Song, Y. Wu,
R. W. Sherwood, T. W. Thannhauser and J. K. C. Rose, Mol.
Cell. Proteomics, 2014, 13, 566–579.
M. Ye, L. Wang and H. Zou, Anal. Chem., 2010, 82, 3007–
3015.
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