75 research outputs found
Characterization of lignin streams during bionic liquid-based tretreatment from grass, hardwood, and softwood
No full textDelignification as a function of ionic liquid (IL) pretreatment has potential in terms of recovering and converting the fractionated lignin streams to renewable products. Renewable biogenic ionic liquids, or bionic liquids (e.g., cholinium lysinate, ([Ch][Lys])), provide opportunities in terms of effective, economic, and sustainable lignocellulosic biomass pretreatment. We have evaluated [Ch][Lys] pretreatment in terms of sugar and lignin yields for three different feedstocks: switchgrass, eucalyptus, and pine. Four lignin streams isolated during [Ch][Lys] pretreatment and enzymatic hydrolysis were comprehensively analyzed, tracking their changes in physical-chemical structures. We observed changes in major lignin linkages and lignin aromatics units (p-hydroxyphenyl (H), guaiacyl (G), and syringil (S)) that occurred during pretreatment. A compositional analysis of the different process streams and a comprehensive mass balance in conjunction with multiple analytical techniques (nuclear magnetic resonance (NMR), mass spectroscopy, gel permeation chromatography (GPC)) is presented. Qualitative and quantitative analyses indicates that there are significantly more lignin-carbohydrate interactions for G-rich lignin in pine. The lignin removal and extent of lignin depolymerization for switchgrass and eucalyptus were higher than pine and follows the order of switchgrass > eucalyptus > pine. The insights gained from this work contribute to better understanding of physiochemical properties of lignin streams generated during [Ch][Lys] pretreatment, offering a starting point for lignin valorization strategies
The dynamics of interleukin-8 and its interaction with human CXC receptor i peptide
No full textInterleukin-8 (CXCL8, IL-8) is a proinflammatory chemokine important for the regulation of inflammatory and immune responses via its interaction with G-protein coupled receptors, including CXC receptor 1 (CXCR1). CXCL8 exists as both a monomer and as a dimer at physiological concentrations, yet the molecular basis of CXCL8 interaction with its receptor as well as the importance of CXCL8 dimer formation remain poorly characterized. Although several biological studies have indicated that both the CXCL8 monomer and dimer are active, biophysical studies have reported conflicting results regarding the binding of CXCL8 to CXCR1. To clarify this problem, we expressed and purified a peptide (hCXCR1pep) corresponding to the N-terminal region of human CXCR1 (hCXCR1) and utilized nuclear magnetic resonance (NMR) spectroscopy to interrogate the binding of wild-type CXCL8 and a previously reported mutant (CXCL8M) that stabilizes the monomeric form. Our data reveal that the CXCL8 monomer engages hCXCR1pep with a slightly higher affinity than the CXCL8 dimer, but that the CXCL8 dimer does not dissociate upon binding hCXCR1pep. These investigations also showed that CXCL8 is dynamic on multiple timescales, which may help explain the versatility in this interleukin for engaging its target receptors
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Changing Safety Culture, One Step at a Time: The Value of the DOE-VPP Program at PNNL
No full textThe primary value of the Pacific Northwest National Laboratory (PNNL) Voluntary Protection Program (VPP) is the ongoing partnership between management and staff committed to change Laboratory safety culture one step at a time. VPP enables PNNL's safety and health program to transcend a top-down, by-the-book approach to safety, and it also raises grassroots safety consciousness by promoting a commitment to safety and health 24 hours a day, 7 days a week. PNNL VPP is a dynamic, evolving program that fosters innovative approaches to continuous improvement in safety and health performance at the Laboratory
Structure and Dynamics of GeoCyp: A Thermophilic Cyclophilin with a Novel Substrate Binding Mechanism That Functions Efficiently at Low Temperatures
No full textThermophilic proteins have found
extensive use in research and
industrial applications because of their high stability and functionality
at elevated temperatures while simultaneously providing valuable insight
into our understanding of protein folding, stability, dynamics, and
function. Cyclophilins, constituting a ubiquitously expressed family
of peptidyl–prolyl isomerases with a range of biological functions
and disease associations, have been utilized both for conferring stress
tolerances and in exploring the link between conformational dynamics
and enzymatic function. To date, however, no active thermophilic cyclophilin
has been fully biophysically characterized. Here, we determine the
structure of a thermophilic cyclophilin (GeoCyp) from <i>Geobacillus
kaustophilus</i>, characterize its dynamic motions over several
time scales using an array of methodologies that include chemical
shift-based methods and relaxation experiments over a range of temperatures,
and measure catalytic activity over a range of temperatures to compare
its structure, dynamics, and function to those of a mesophilic counterpart,
human cyclophilin A (CypA). Unlike those of most thermophile/mesophile
pairs, GeoCyp catalysis is not substantially impaired at low temperatures
as compared to that of CypA, retaining ∼70% of the activity
of its mesophilic counterpart. Examination of substrate-bound ensembles
reveals a mechanism by which the two cyclophilins may have adapted
to their environments through altering dynamic loop motions and a
critical residue that acts as a clamp to regulate substrate binding
differentially in CypA and GeoCyp. Fast time scale (pico- to nanosecond)
dynamics are largely conserved between the two proteins, in accordance
with the high degree of structural similarity, although differences
do exist in their temperature dependencies. Slower (microsecond) time
scale motions are likewise localized to similar regions in the two
proteins with some variability in their magnitudes yet do not exhibit
significant temperature dependencies in either enzyme
Studies of Secondary Melanoma on C57BL/6J Mouse Liver Using 1H NMR Metabolomics
No full textNMR metabolomics, consisting of solid state high resolution magic angle spinning (HR-MAS) 1H-NMR, liquid state high resolution 1H-NMR, and principal components analysis (PCA) has been used to study secondary metastatic B16-F10 melanoma in C57BL/6J mouse liver. The melanoma group can be differentiated from its control group by PCA analysis of the estimates of absolute concentrations from liquid state 1H-NMR spectra on liver tissue extracts or by the estimates of absolute peak intensities of metabolites from 1H HR-MAS-NMR data on intact liver tissues. In particular, we found that the estimates of absolute concentrations of glutamate, creatine, fumarate and cholesterol are elevated in the melanoma group as compared to controls, while the estimates of absolute concentrations of succinate, glycine, glucose, and the family of linear lipids including long chain fatty acids, total choline and acyl glycerol are decreased. The ratio of glycerophosphocholine (GPC) to phosphocholine (PCho) is increased by about 1.5 fold in the melanoma group, while the estimate of absolute concentration of total choline is actually lower in melanoma mice. These results suggest the following picture in secondary melanoma metastasis: Linear lipid levels are decreased by beta oxidation in the melanoma group, which contributes to an increase in the synthesis of cholesterol, and also provides an energy source input for TCA cycle. These findings suggest a link between lipid oxidation, the TCA cycle and the hypoxia-inducible factors (HIF) signal pathway in tumor metastases. Thus, this study indicates that the metabolic profile derived from NMR analysis can provide a valuable bio-signature of malignancy and cell hypoxia in metastatic melanoma
PG1258+593 and its common proper motion magnetic white dwarf counterpart
No full textWe confirm SDSS J130033.48+590407.0 as a common proper motion companion to the well-studied hydrogen-atmosphere (DA) white dwarf PG1258+593 (GD322). The system lies at a distance of 68 +/- 3 pc, where the angular separation of 16.1 +/- 0.1 arcsec corresponds to a minimum binary separation of 1091 +/- 7 au. SDSS J1300+5904 is a cool (T-eff = 6300 +/- 300 K) magnetic white dwarf (B similar or equal to 6 mG). PG1258+593 is a DA white dwarf with T-eff = 14790 +/- 77K and log g = 7.87 +/- 0.02. Using the white dwarf mass-radius relation implies the masses of SDSS J1300+5904 and PG 1258+593 are 0.54 +/- 0.06 and 0.54 +/- 0.01M(circle dot), respectively, and therefore a cooling age difference of 1.67 +/- 0.05 Gyr. Adopting main-sequence lifetimes from stellar models, we derive an upper limit of 2.2M(circle dot) for the mass of the progenitor of PG 1258+593. A plausible range of initial masses is 1.4-1.8 M-circle dot for PG1258+593 and 2-3M(circle dot) for SDSS J1300+5904. Our analysis shows that white dwarf common proper motion binaries can potentially constrain the white dwarf initial mass-final mass relation and the formation mechanism for magnetic white dwarfs. The magnetic field of SDSS J1300+5904 is consistent with an Ap progenitor star. A common envelope origin of the system cannot be excluded, but requires a triple system as progenitor
Flux rates for total citric acid cycle (CAC) and individual substrates at standard afterload.
No full text<p>Units are µmol/g/min. Values are means±SEM. n = 4 per group. * p<0.05.</p
Flux rates for total citric acid cycle (CAC) and individual substrates at high afterload.
No full text<p>Units are µmol/g/min. Values are means±SEM. n = 5–8 per group.</p>*<p>p<0.05 versus Young;</p>#<p>p<0.05 versus Old-TH;</p>$<p>p<0.05 versus Old.</p
Metabolic Response of the Immature Right Ventricle to Acute Pressure Overloading
No full text
Background
Surgical palliation or repair of complex congenital heart disease in early infancy can produce right ventricular (
RV
) pressure overload, often leading to acute hemodynamic decompensation. The mechanisms causing this acute
RV
dysfunction remain unclear. We tested the hypothesis that the immature right ventricle lacks the ability to modify substrate metabolism in order to meet increased energy demands induced by acute pressure overloading.
Methods and Results
Twenty‐two infant male mixed breed Yorkshire piglets were randomized to a sham operation (Control) or pulmonary artery banding yielding >2‐fold elevation over baseline
RV
systolic pressure. We used carbon 13 (
13
C)‐labeled substrates and proton nuclear magnetic resonance to assess
RV
energy metabolism. [Phosphocreatine]/[
ATP
] was significantly lower after pulmonary artery banding. [Phosphocreatine]/[
ATP
] inversely correlated with energy demand indexed by maximal sustained
RV
systolic pressure/left ventricular systolic pressure. Fractional contributions of fatty acids to citric acid cycle were significantly lower in the pulmonary artery banding group than in the Control group (medium‐chain fatty acids; 14.5±1.6 versus 8.2±1.0%, long‐chain fatty acids; 9.3±1.5 versus 5.1±1.1%).
13
C‐flux analysis showed that flux via pyruvate decarboxylation did not increase during
RV
pressure overloading.
Conclusions
Acute
RV
pressure overload yielded a decrease in [phosphocreatine]/[
ATP
] ratio, implying that
ATP
production did not balance the increasing
ATP
requirement. Relative fatty acids oxidation decreased without a reciprocal increase in pyruvate decarboxylation. The data imply that
RV
inability to adjust substrate oxidation contributes to energy imbalance, and potentially to contractile failure. The data suggest that interventions directed at increasing
RV
pyruvate decarboxylation flux could ameliorate contractile dysfunction associated with acute pressure overloading.
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