20 research outputs found
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A Method for In-Depth Structural Annotation of Human Serum Glycans That Yields Biological Variations
Glycosylation is an important post-translational
modification of
proteins present in the vast majority of human proteins. For this
reason, they are potentially new sources of biomarkers and active
targets of therapeutics and vaccines. However, the absence of a biosynthetic
template as in the genome and the general complexity of the structures
have limited the development of methods for comprehensive structural
analysis. Even now, the exact structures of many abundant N-glycans
in serum are not known. Structural elucidation of oligosaccharides
remains difficult and time-consuming. Here, we introduce a means of
rapidly identifying released N-glycan structures using their accurate
masses and retention times based on a glycan library. This serum glycan
library, significantly expanded from a previous one covering glycans
released from a handful of serum glycoproteins, has more than 170
complete and partial structures and constructed instead from whole
serum. The method employs primarily nanoflow liquid chromatography
and accurate mass spectrometry. The method allows us to readily profile
N-glycans in biological fluids with deep structural analysis. This
approach is used to determine the relative abundances and variations
in the N-glycans from several individuals providing detailed variations
in the abundances of the important N-glycans in blood
Fluorescent Recognition of Zn<sup>2+</sup> by Two Diastereomeric Salicylaldimines: Dramatically Different Responses and Spectroscopic Investigation
Fluorescence responses
of two BINOL-based diastereomeric salicylaldimines toward a variety
of metal cations have been studied in methanol solution. It is revealed
that both compounds show great fluorescence enhancements in the presence
of Zn<sup>2+</sup> but not with any other metal ions. Moreover, these
two diastereomers exhibit dramatically different responses toward
Zn<sup>2+</sup> under the same conditions. That is, one can produce
much stronger fluorescence enhancement also at a longer wavelength
than the other. This fluorescence recognition of Zn<sup>2+</sup> also
shows distinctive color changes under a UV lamp. Mass and NMR spectroscopic
analyses have been used to study the mechanism, which indicates the
formation of 2+<i>n</i>Zn<sup>2+</sup> complexes (<i>n</i> = 2, 3). This work has shed new light on the mechanism
of an enantioselective fluorescent recognition of chiral amines promoted
by Zn<sup>2+</sup>
In-Depth Method for the Characterization of Glycosylation in Manufactured Recombinant Monoclonal Antibody Drugs
The glycosylation in recombinant
monoclonal antibody (rMab) drugs
is a major concern in the biopharmaceutical industry as it impacts
the drugs’ many attributes. Characterization is important but
complicated by the intricate structures, microheterogeneity, and the
limitations of current tools for structural analysis. In this study,
we developed a liquid chromatography–mass spectrometry (LC–MS)
N-glycan library based on eight commercial rMab drugs. A library of
over 70 structures was developed for the rapid characterization of
rMab. N-Glycans were separated on a porous graphitized carbon (PGC)
column incorporated on a chip and then analyzed by an electrospray
ionization hybrid quadrupole time-of-flight (ESI-Q-TOF) MS. The retention
time and accurate mass for each N-glycan were recorded in the library.
The complete structures were obtained through exoglycosidase sequencing.
The results showed that most of the N-glycans between different antibodies
are nearly the same with different abundances. The utility of this
library enables one to identify structures in a rapid manner by matching
LC retention times and accurate masses
Correction to 3‑Thiomorpholin-8-oxo‑8<i>H</i>‑acenaphtho[1,2‑<i>b</i>]pyrrole-9-carbonitrile (S1) Based Molecules as Potent, Dual Inhibitors of B‑Cell Lymphoma 2 (Bcl-2) and Myeloid Cell Leukemia Sequence 1 (Mcl-1): Structure-Based Design and Structure–Activity Relationship Studies
Correction to 3‑Thiomorpholin-8-oxo‑8<i>H</i>‑acenaphtho[1,2‑<i>b</i>]pyrrole-9-carbonitrile
(S1) Based Molecules as Potent, Dual Inhibitors of B‑Cell Lymphoma
2 (Bcl-2) and Myeloid Cell Leukemia Sequence 1 (Mcl-1): Structure-Based
Design and Structure–Activity Relationship Studie
Gas-Exfoliation Assisted Fabrication of Porous Graphene Nanosheets Derived from <i>Plumeria rubra</i> for Highly Efficient Photocatalytic Hydrogen Evolution
An environmentally
friendly strategy was performed to prepare porous
graphene nanosheets (PGS) through gas-exfoliation assisted KOH activation
by using Plumeria rubra as the precursor
for the first time. Because the synergistic reaction of various graphitization
temperature and activating agent amounts, the precursor was gradually
exfoliated by released gases, graphitizing at high temperatures and
forming porous graphene nanosheets during the graphitization. PGS-2-1000
with a hierarchical porous structure possessed high graphitization
(<i>I</i><sub>D</sub>/<i>I</i><sub>G</sub> = 0.77, <i>I</i><sub>2D</sub>/<i>I</i><sub>G</sub> = 0.53), ultrahigh
specific surface (1581 m<sup>2</sup> g<sup>–1</sup>) and large
pore volume (0.916 cm<sup>3</sup> g<sup>–1</sup>). A facile <i>in situ</i> photoreduction treatment was utilized to form a
Cu/PGS photocatalyst composed of nonsemiconductor plasmonic Cu NPs
and porous graphene nanosheets, exhibiting the hydrogen evolution
rate of 4.87 mmol g<sup>–1</sup> h<sup>–1</sup>, which
is 4-fold as high as that of single Cu NPs. The photostability of
Cu/PGS-2-1000 was investigated in five consecutive runs of 30 h accumulative
irradiation. The PGS could act as an electron transport bridge to
boost the separation of electron–hole pairs and the uniform
distribution of Cu NPs, even serve as a photocatalyst for hydrogen
generation. Furthermore, a possible mechanism was proposed to illustrate
the circumstantial charge transfer channel as well as the improvement
of photocatalytic activity
Quantitation of Site-Specific Glycosylation in Manufactured Recombinant Monoclonal Antibody Drugs
During the development
of recombinant monoclonal antibody (rMAb) drugs, glycosylation receives
particular focus because changes in the attached glycans can have
a significant impact on the antibody effector functions. The vast
heterogeneity of structures that exist across glycosylation sites
hinders the in-depth analysis of glycan changes specific to an individual
protein within a complex mixture. In this study, we established a
sensitive and specific method for monitoring site-specific glycosylation
in rMAbs using multiple reaction monitoring (MRM) on an ultrahigh-performance
liquid chromatography–triple quadrupole MS (UHPLC-QqQ-MS).
Our results showed that irrespective of the IgG subclass expressed
in the drugs, the N-glycopeptide profiles are nearly the same but
differ in abundances. In all rMAb drugs, a single subclass of IgG
comprised over 97% of the total IgG content and showed over 97% N-glycan
site occupancy. This study demonstrates the utility of an MRM-based
method to rapidly characterize over 130 distinct glycopeptides and
determine the extent of site occupancy within minutes. Such multilevel
structural characterization is important for the successful development
of therapeutic antibodies
Dosimetric endpoints and criteria for assessing IMRT plan quality.
<p>Dosimetric endpoints and criteria for assessing IMRT plan quality.</p
Bcl-2/MDM2 Dual Inhibitors Based on Universal Pyramid-Like α‑Helical Mimetics
No
α-helical mimetic that exhibits Bcl-2/MDM2 dual inhibition
has been rationally designed due to the different helicities of the
α-helixes at their binding interfaces. Herein, we extracted
a one-turn α-helix-mimicking <i>ortho</i>-triarene
unit from <i>o</i>-phenylene foldamers. Linking benzamide
substrates with a rotatable C–N bond, we constructed a novel
semirigid pyramid-like scaffold that could support its two-turn α-helix
mimicry without aromatic stacking interactions and could adopt the
different dihedral angles of the key residues of p53 and BH3-only
peptides. On the basis of this universal scaffold, a series of substituent
groups were installed to capture the key residues of both p53TAD and
BimBH3 and balance the differences of the bulks between them. Identified
by FP, ITC, and NMR spectroscopy, a compound <b>6e</b> (<b>zq</b>-<b>1</b>) that directly binds to Mcl-1, Bcl-2, and
MDM2 with balanced submicromolar affinities was obtained. Cell-based
experiments demonstrated its antitumor ability through Bcl-2/MDM2
dual inhibition simultaneously
A QC report example for one clinically approved cervical cancer IMRT plan.
<p>A QC report example for one clinically approved cervical cancer IMRT plan.</p