2 research outputs found
Stabilization of Natural Organic Matter by Short-Range-Order Iron Hydroxides
Dissolved organic matter (DOM) is
capable of modifying the surfaces
of soil minerals (e.g., Fe hydroxides) or even forming stable co-precipitates
with FeÂ(III) in a neutral environment. The DOM/Fe co-precipitation
may alter biogeochemical carbon cycling in soils if the relatively
mobile DOM is sorbed by soil minerals against leaching, runoff, and
biodegradation. In this study, we aimed to determine the structural
development of DOM/Fe co-precipitates in relation to changes in pH
and C/(C + Fe) ratios using XRD, XPS, Fe K-edge XAS, FTIR, and C-NEXAFS
techniques. The results showed that in the system with bulk C/(C +
Fe) molar ratios ≤0.65, the ferrihydrite-like Fe domains were
precipitated as the core and covered by the C shells. When the C/(C
+ Fe) molar ratio ranged between 0.71 and 0.89, the emerging Fe–C
bonding suggested a more substantial association between Fe domains
including edge- and corner-sharing FeO<sub>6</sub> octahedra and DOM.
With C/(C + Fe) bulk molar ratios ≥0.92, only corner-sharing
FeO<sub>6</sub> octahedra along with Fe–C bonding were found.
The homogeneously distributed C and Fe domains caused the enhancement
of Fe and C solubilization from co-precipitates. The C/(C + Fe) ratios
dominated structural compositions and stabilities of C/Fe co-precipitates
and may directly affect the Fe and C cycles in soils
Role of N‑Linked Glycans in the Interactions of Recombinant HCV Envelope Glycoproteins with Cellular Receptors
Hepatitis C virus (HCV) infection
is a major cause of chronic hepatitis
and hepatocellular carcinoma. It infects human liver cells through
several cellular protein receptors including CD81, SR-BI, claudin-1,
and occludin. Previous reports also show that lectin receptors can
mediate HCV recognition and entry. The envelope proteins of HCV (E1
and E2) are heavily glycosylated, further indicating the possible
roles of lectin receptor–virus interaction in HCV infection.
However, there is limited study investigating the relationship of
HCV envelope glycoproteins and lectin as well as non-lectin receptors.
Here we used surface plasmon resonance to examine the binding affinity
of different glycoforms of recombinant HCV envelope protein to receptors
and inspected the infectivity and assembly of HCV pseudoparticles
composed of different glycoforms of envelope proteins. Our results
indicated that DC-SIGN, L-SIGN, and Langerin had higher affinity to
recombinant HCV envelope proteins in the presence of calcium ions
than non-lectin receptors, and envelope proteins with Man8/9 N-glycans
showed approximate 10-fold better binding to lectin receptors than
envelope proteins with Man5 and complex type N-glycans. Interestingly,
comparing among glycoforms, recombinant envelope proteins with Man5
N-glycans showed the highest binding affinity when interacting with
non-lectin receptors. In summary, the glycans on HCV envelope protein
play a modulatory role in HCV assembly and infection and direct HCV–receptor
interaction, which mediates viral entry in different cells. Receptors
with high affinity to HCV envelope proteins may be considered as targets
for development of a therapeutic strategy against HCV