4 research outputs found
A Clean and General Strategy To Decorate a Titanium Metal–Organic Framework with Noble-Metal Nanoparticles for Versatile Photocatalytic Applications
We demonstrate a facile and general
approach for the fabrication
of highly dispersed Au, Pd, and Pt nanoparticles (NPs) on MIL-125Â(Ti)
without using extra reducing and capping agents. Noble-metal NP formation
is directed by an in situ redox reaction between the reductive MIL-125Â(Ti)
with Ti<sup>3+</sup> and oxidative metal salt precursors. The resulting
composites function as efficient photocatalysts
Simplified Quantitative Glycomics Using the Stable Isotope Label Girard’s Reagent P by Electrospray Ionization Mass Spectrometry
Fast,
sensitive, and simple methods for quantitative analysis of
disparities in glycan expression between different biological samples
are essential for studies of protein glycosylation patterns (glycomics)
and the search for disease glycan biomarkers. Relative quantitation
of glycans based on stable isotope labeling combined with mass spectrometric
detection represents an emerging and promising technique. However,
this technique is undermined by the complexity of mass spectra of
isotope-labeled glycans caused by the presence of multiple metal ion
adduct signals, which result in a decrease of detection sensitivity
and an increase of difficulties in data interpretation. Herein we
report a simplified quantitative glycomics strategy, which features
nonreductive isotopic labeling of reducing glycans with either nondeuterated
(<i>d</i><sub>0</sub>-) or deuterated (<i>d</i><sub>5</sub>-) Girard’s reagent P (GP) without salts introduced
and simplified mass spectrometric profiles of <i>d</i><sub>0</sub>- and <i>d</i><sub>5</sub>-GP derivatives of neutral
glycans as molecular ions without complex metal ion adducts, allowing
rapid and sensitive quantitative comparison between different glycan
samples. We have obtained optimized GP-labeling conditions and good
quantitation linearity, reproducibility, and accuracy of data by the
method. Its excellent applicability was validated by comparatively
quantitative analysis of the neutral <i>N</i>-glycans released
from bovine and porcine immunoglobulin G as well as of those from
mouse and rat sera. Additionally, we have revealed the potential of
this strategy for the high-sensitivity analysis of sialylated glycans
as GP derivatives, which involves neutralization of the carboxyl group
of sialic acid by chemical derivatization
Simultaneous Release and Labeling of <i>O</i>- and <i>N</i>‑Glycans Allowing for Rapid Glycomic Analysis by Online LC-UV-ESI-MS/MS
Most
glycoproteins and biological protein samples undergo both <i>O</i>- and <i>N</i>-glycosylation, making characterization
of their structures very complicated and time-consuming. Nevertheless,
to fully understand the biological functions of glycosylation, both
the glycosylation forms need to be analyzed. Herein we report a versatile,
convenient one-pot method in which <i>O</i>- and <i>N</i>-glycans are simultaneously released from glycoproteins
and chromogenically labeled in situ and thus available for further
characterization. In this procedure, glycoproteins are incubated with
1-phenyl-3-methyl-5-pyrazolone (PMP) in aqueous ammonium hydroxide,
making <i>O</i>-glycans released from protein backbones
by β-elimination and <i>N</i>-glycans liberated by
alkaline hydrolysis. The released glycans are promptly derivatized
with PMP in situ by Knoevenagel condensation and Michael addition,
with peeling degradation almost completely prevented. The recovered
mixture of <i>O</i>- and <i>N</i>-glycans as bis-PMP
derivatives features strong ultraviolet (UV) absorbing ability and
hydrophobicity, allowing for high-resolution chromatographic separation
and high-sensitivity spectrometric detection. Using this technique, <i>O</i>- and <i>N</i>-glycans were simultaneously prepared
from some model glycoproteins and complex biological samples, without
significant peeling, desialylation, deacetylation, desulfation or
other side-reactions, and then comprehensively analyzed by online
HILIC-UV-ESI-MS/MS and RP-HPLC-UV-ESI-MS/MS, with which some novel <i>O</i>- and <i>N</i>-glycan structures were first found.
This method provides a simple, versatile strategy for high-throughput
glycomics analysis
Mass Spectrometric Analysis of <i>N</i>‑Glycoforms of Soybean Allergenic Glycoproteins Separated by SDS-PAGE
Glycosylation
of many proteins has been revealed to be closely related with food
allergies, and screening and structural analysis of related glycoproteins
and glycoallergens are essential for studies in this field. Herein,
we describe detailed <i>N</i>-glycoform analysis of all
glycoprotein fractions of soybean protein isolate (SPI) separated
by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE)
to disclose structural features of the glycan moieties of more soybean
glycoproteins. SPI was fractionated by SDS-PAGE, and the generated
protein bands were recovered and subjected to in-gel <i>N</i>-glycan release and labeling using a one-pot method newly developed
by our group, followed by detailed analysis by electrospray ionization
mass spectrometry (ESI-MS) and online hydrophilic interaction liquid
chromatography coupled with electrospray ionization tandem mass spectrometry
(HILIC-ESI-MS/MS). As a result, we found seven bands mainly containing
oligomannose-type glycans; two mainly contain core α1,3-fucosylated
glycans, and six have no glycans. This study is the first report that
discovers core α1,3-fucosylated <i>N</i>-glycans in
bands 1, 2, and 6 and discloses bands 3, 4, 5, and 7 as glycoproteins
and their <i>N</i>-glycoforms. Therefore, it can expand
our knowledge about soybean protein glycosylation and provide significant
structural reference for research of soybean allergens