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1.
Debbie C. Crans Samantha Schoeberl Ernestas Gaidamauskas Bharat Baruah Deborah A. Roess 《Journal of biological inorganic chemistry》2011,16(6):961-972
The interactions of metabolites of the antidiabetic vanadium-containing drug bis(maltolato)oxovanadium(IV) (BMOV) with lipid
interface model systems were investigated and the results were used to describe a potentially novel mechanism by which these
compounds initiate membrane-receptor-mediated signal transduction. Specifically, spectroscopic studies probed the BMOV oxidation
and hydrolysis product interaction with interfaces created from cetyltrimethylammonium bromide (CTAB) which mimics the positively
charged head group on phosphatidylcholine. 1H and 51V NMR spectroscopies were used to determine the location of the dioxobis(maltolato)oxovanadate(V) and the maltol ligand in
micelles and reverse micelles by measuring changes in the chemical shift, signal linewidth, and species distribution. Both
micelles and reverse micelles interacted similarly with the complex and the ligand, suggesting that interaction is strong
as anticipated by Coulombic attraction between the positively charged lipid head group and the negatively charged complex
and deprotonated ligand. The nature of the model system was confirmed using dynamic light scattering studies and conductivity
measurements. Interactions of the complex/ligand above and below the critical micelle concentration of micelle formation were
different, with much stronger interactions when CTAB was in the form of a micelle. Both the complex and the ligand penetrated
the lipid interface and were located near the charged head group. These studies demonstrate that a lipid-like interface affects
the stability of the complex and raise the possibility that ligand exchange at the interface may be important for the mode
of action for these systems. Combined, these studies support recently reported in vivo observations of BMOV penetration into
3T3-L1 adipocyte membranes and increased translocation of a glucose transporter to the plasma membrane. 相似文献
2.
Ernestas Gaidamauskas Kanokkarn Saejueng Alvin A. Holder Subalita Bharuah Boris A. Kashemirov Debbie C. Crans Charles E. McKenna 《Journal of biological inorganic chemistry》2008,13(8):1291-1299
Metal complexation reactions can be used effectively as sensors to measure concentrations of phosphate and phosphate analogs.
Recently, a method was described for the detection of phosphate or ATP in aqueous solution based on the displacement by these
ligands of pyrocatechol violet (PV) from a putative 2:1 (Yb3+)2PV complex. We have not been able to reproduce this stoichiometry and report this work in order to correct the coordination
chemistry upon which sensor applications are based. In our work, colorimetric and spectrophotometric detection of phosphate
was confirmed qualitatively (blue PV + Yb3+; yellow + Pi); however, the sequence of visual changes on the titration of PV with 2 equiv. of Yb3+ and back titration with ATP as described previously could not be reproduced. In contrast to the linear response to Pi that was reported previously, the absorbance response at 443 or 623 nm was found to be sigmoidal using the recommended 2:1
Yb3+:PV solution (100 μM:50 μM, pH 7, HEPES). Furthermore, both continuous variation titration and molar ratio analysis (Job plot)
experiments are consistent with 1:1, not 2:1, YbPV complex stoichiometry at pH 7 in HEPES buffer, indicating that the deviation
from linearity is produced by excess Yb3+. Indeed, using a 1:1 Yb3+:PV ratio produces a linear response in ΔAbs at 443 or 623 nm on back titration with analyte (phosphate or ATP). In addition,
speciation analysis of the Yb–ATP system demonstrates that a 1:1 complex containing Yb3+ and ATP predominates in solution at μM metal ion and ATP concentrations. Paramagnetic 1H NMR spectroscopy directly establishes the formation of Yb3+–solute complexes in dilute aqueous solution. The 1:1 YbPV complex can be used for the colorimetric measurement of phosphate
and ATP concentrations from ~2 μM.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Charles E. McKenna (Corresponding author)Email: |
3.
Crans DC Smee JJ Gaidamauskiene EG Anderson OP Miller SM Jin W Gaidamauskas E Crubellier E Grainda R Chi LH Willsky GR 《Journal of inorganic biochemistry》2004,98(11):1837-1850
The effects of Mo-hydroxylamido complexes on cell growth were determined in Saccharomyces cerevisiae to investigate the biological effects of four different Mo complexes as a function of pH. Studies with yeast, an eukaryotic cell, are particularly suited to examine growth at different pH values because this organism grows well from pH 3 to 6.5. Studies can therefore be performed both in the presence of intact complexes and when the complexes have hydrolyzed to ligand and free metal ion. One of the complexes we examined was structurally characterized by X-ray crystallography. Yeast growth was inhibited in media solutions containing added Mo-dialkylhydroxylamido complexes at pH 3-7. When combining the yeast growth studies with a systematic study of the Mo-hydroxylamido complexes' stability as a function of pH and an examination of their speciation in yeast media, the effects of intact complexes can be distinguished from that of ligand and metal. This is possible because different effects are observed with complex present than when ligand or metal alone is present. At pH 3, the growth inhibition is attributed to the forms of molybdate ion that exist in solution because most of the complexes have hydrolyzed to oxomolybdate and ligand. The monoalkylhydroxylamine ligand inhibited yeast growth at pH 5, 6 and 7, while the dialkylhydroxylamine ligands had little effect on yeast growth. Growth inhibition of the Mo-dialkylhydroxylamido complexes is observed when a complex exists in the media. A complex that is inert to ligand exchange is not effective even at pH 3 where other Mo-hydroxylamido complexes show growth inhibition as molybdate. These results show that the formation of some Mo complexes can protect yeast from the growth inhibition observed when either the ligand or Mo salt alone are present. 相似文献
4.
Norkus E Vaiciūniene J Vuorinen T Gaidamauskas E Reklaitis J Jääskeläinen AS Crans DC 《Carbohydrate research》2004,339(3):599-605
The formation of four Cu(II)-xylitol complexes was observed in aqueous alkaline solutions (11.0< or =pH< or =14.0, I=1.0, 20 degrees C) by means of direct current polarography and VIS spectrophotometry. Mononuclear hydroxy complexes, CuXyl(OH)- (log beta=17.7 +/- 0.5), CuXyl(OH)2(2-) (log beta=20.2 +/- 0.3) and CuXyl2(OH)2(4-) (log beta=22.4 +/- 0.3), are formed at high ligand-to-metal ratios (L:M> or =10), whereas dinuclear complex Cu2Xyl (log beta=29.2 +/- 0.3) is the predominant species at low ligand-to-metal ratio (L:M=0.5). Diffusion coefficients and molar absorptivities of the complex species were determined. pH variable 13C NMR suggested that pKa values of xylitol are rather similar and equal to 13.8 +/- 0.2, 13.9 +/- 0.1 and 13.9 +/- 0.2 for OH-groups adjacent to (C-1,C-5), (C-3) and (C-2,C-4) carbon atoms, respectively. 相似文献
5.
Agata Karklelyte Konstantinas Povilas Valuckas Romas Griskevicius Ernestas Janulionis Eduardas Aleknavicius 《Reports of Practical Oncology and Radiotherapy》2018,23(4):284-289
Purpose
The aim of our study was to perform the final analysis of acute toxicity and quality of life data obtained from 221 consecutive patients who suffered from intermediate-to-high risk prostate cancer.Methods
In this trial, 221 patients were randomized to receive either hypofractionated (63?Gy in 20 fractions, 4 fractions/week) or conventionally fractionated (76?Gy in 38 fractions, 5 fractions/week) radiotherapy to the prostate and seminal vesicles. Elective pelvic lymph node irradiation with 46?Gy in 23 fractions sequentially and 44?Gy in 20 fractions simultaneously was also applied.Results
There was no statistically significant difference in acute GU and GI toxicity in men treated with hypofractionated (SIB) (Arm 2) in comparison with patients who had conventional fractionation (Arm 1) radiation therapy. Multivariate analysis using logistic regression showed statistical significant association between acute GU?≥?1 and PTV(LN) (p?=?0.008) only. We found out that clinically relevant decrease (CRD) was significantly higher only in the urinary domain of Arm 1 at month 3 (p?=?0.02).Conclusion
Our study demonstrated that hypofractionated radiotherapy was associated with a small but insignificant increase of acute toxicity. The reduction of overall treatment time has no significant influence on patients’ QOL in any domain. 相似文献6.
Variable pH 13C NMR and 1H NMR spectroscopic studies of the β-cyclodextrin (β-CD) in alkaline aqueous solutions revealed that β-CD does not deprotonate at pH < 12.0. Further increase in solution pH results in the deprotonation of OH-groups adjacent to C-2 and C-3 carbon atoms of β-CD glucopyranose units, whereas the deprotonation of OH-groups adjacent to C-6 carbon atoms is expressed less markedly. The pKa values for β-CD OH-groups adjacent to C-2 and C-3 carbon atoms are rather close, pKa1,2 being 13.5 ± 0.2 (22.5 °C). 相似文献
7.
Ervinas Gaidamauskas Claus GyrupHenning B. Boldt Vivien R. SchackMichael T. Overgaard Lisbeth S. LaursenClaus Oxvig 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Pregnancy-associated plasma protein-A (PAPP-A) is a local regulator of insulin-like growth factor (IGF) bioavailability in physiological systems, but many structural and functional aspects of the metzincin metalloproteinase remain to be elucidated. PAPP-A cleaves IGF binding protein (IGFBP)-4 and IGFBP-5. Cleavage of IGFBP-4, but not IGFBP-5, depends on the binding of IGF before proteolysis by PAPP-A can occur. The paralogue PAPP-A2 has two substrates among the six IGFBPs: IGFBP-3 and IGFBP-5.Methods
Sets of chimeric proteins between IGFBP-4 and -5, and IGFBP-3 and -5 were constructed to investigate the structural requirements for IGF modulation. At the proteinase level, we investigated the importance of individual acidic amino acids positioned in the proteolytic domain of PAPP-A for proteolytic activity against IGFBP-4 and -5. Interaction between PAPP-A and its substrates was analyzed by surface plasmon resonance.Results and conclusion
We provide data suggesting that the C-terminal domain of the IGFBPs is responsible for IGF-dependent modulation of access to the scissile bond. Loss or reduction of IGFBP proteolysis by PAPP-A was observed upon mutation of residues positioned in the unique 63-residue stretch separating the zinc and Met-turn motifs, and in the short sequence following the Met-turn methionine. A model of the proteolytic domain of PAPP-A suggests the presence of structural calcium ions in the C-terminal subdomain, implicated in IGFBP substrate interactions.General significance
Detailed knowledge of interactions between PAPP-A and its substrates is required to understand the modulatory role of PAPP-A on IGF receptor stimulation. 相似文献8.
Wendy?E.?Heywood Daniela?Galimberti Emily?Bliss Ernestas?Sirka Ross?W.?Paterson Nadia?K.?Magdalinou Miryam?Carecchio Emma?Reid Amanda?Heslegrave Chiara?Fenoglio Elio?Scarpini Jonathan?M.?Schott Nick?C.?Fox John?Hardy Kailash?Bahtia Simon?Heales Neil?J.?Sebire Henrik?Zetterburg Kevin?MillsEmail author 《Molecular neurodegeneration》2015,10(1):64
Background
Currently there are no effective treatments for many neurodegenerative diseases. Reliable biomarkers for identifying and stratifying these diseases will be important in the development of future novel therapies. Lewy Body Dementia (LBD) is considered an under diagnosed form of dementia for which markers are needed to discriminate LBD from other forms of dementia such as Alzheimer’s Disease (AD). This work describes a Label-Free proteomic profiling analysis of cerebral spinal fluid (CSF) from non-neurodegenerative controls and patients with LBD. Using this technology we identified several potential novel markers for LBD. These were then combined with other biomarkers from previously published studies, to create a 10 min multiplexed targeted and translational MRM-LC-MS/MS assay. This test was used to validate our new assay in a larger cohort of samples including controls and the other neurodegenerative conditions of Alzheimer’s and Parkinson’s disease (PD).Results
Thirty eight proteins showed significantly (p?<?0.05) altered expression in LBD CSF by proteomic profiling. The targeted MRM-LC-MS/MS assay revealed 4 proteins that were specific for the identification of AD from LBD: ectonucleotide pyrophosphatase/phosphodiesterase 2 (p?<?0.0001), lysosome-associated membrane protein 1 (p?<?0.0001), pro-orexin (p?<?0.0017) and transthyretin (p?<?0.0001). Nineteen proteins were elevated significantly in both AD and LBD versus the control group of which 4 proteins are novel (malate dehydrogenase 1, serum amyloid A4, GM2?activator protein, and prosaposin). Protein-DJ1 was only elevated significantly in the PD group and not in either LBD or AD samples. Correlations with Alzheimer-associated amyloid β-42 levels, determined by ELISA, were observed for transthyretin, GM2 activator protein and IGF2 in the AD disease group (r2?≥?0.39, p?≤?0.012). Cystatin C, ubiquitin and osteopontin showed a strong significant linear relationship (r2?≥?0.4, p?≤?0.03) with phosphorylated–tau levels in all groups, whilst malate dehydrogenase and apolipoprotein E demonstrated a linear relationship with phosphorylated-tau and total-tau levels in only AD and LBD disease groups.Conclusions
Using proteomics we have identified several potential and novel markers of neurodegeneration and subsequently validated them using a rapid, multiplexed mass spectral test. This targeted proteomic platform can measure common markers of neurodegeneration that correlate with existing diagnostic makers as well as some that have potential to show changes between AD from LBD.9.
Debbie C. Crans Bharat Baruah Ernestas Gaidamauskas Brant G. Lemons Bret B. Lorenz Michael D. Johnson 《Journal of inorganic biochemistry》2008,102(5-6):1334
The anti-oxidant properties of l-ascorbic acid were investigated in the confined medium produced by a sodium bis(2-ethylhexyl)sulfosuccinate (aerosol-OT, AOT) self-assembled reverse micelle. Using 1H–1H NOESY (proton-proton 2D nuclear overhauser enhancement correlation spectroscopy) NMR spectroscopy, the location of ascorbic acid was investigated and found to be at the AOT-interface in contrast to earlier studies where the ascorbate was assumed to be in the water pool in these microemulsions. The reaction of ascorbic acid with oxygen was investigated using EPR spectroscopy. A delocalized monoanionic ascorbate radical was observed in microemulsions prepared from pH 5.6 stock solutions. This is in contrast to studies carried out in aqueous media where no radical formation was observed. The oxidation of ascorbic acid by aqueous V(V) was investigated in reverse micelles. Modest changes in the kinetic parameters were observed for this system compared to that in water. Details of these reactions were examined and can be summarized as the microemulsion solvating and stabilizing reactive intermediates via rate inhibition or enhancement. The inhibition of the oxidation is due to solvation stabilization of ascorbic acid in microemulsion media. Since ascorbate is a valuable marker of oxidative stress, our results suggest that compartmentization can modify the stabilization of the ascorbate radical and the changes in properties could be important in biological systems. 相似文献
10.
Ernestas Gaidamauskas Boris A. Kashemirov Kanokkarn Saejueng Charles E. McKenna Debbie C. Crans 《Journal of inorganic biochemistry》2009,103(12):1652-1657
The coordination chemistry of bisphosphonates with Yb3+ was investigated to evaluate the potential of the UV-vis based detection method using the Yb3+-pyrocatechol complexation reaction as a sensor for bisphosphonates. The complexation chemistry of Yb3+ with phosphate and ATP analogs was previously described (E. Gaidamauskas, K. Saejueng, A.A. Holder, S. Bharuah, B.A. Kashemirov, D.C. Crans, C.E. McKenna, J. Biol. Inorg. Chem. 13 (2008) 1291-1299), and we here studied the complexation chemistry of bisphosphonates in this system. The spectrophotometric assay yields direct evidence for formation of a 4:3 metal to ligand complex at neutral pH. Direct evidence for Yb3+:methylenebis(phosphonate) complexes with 1:1 and 1:2 stoichiometry was also obtained by potentiometry at acidic and basic pH. Direct evidence for complex formation was obtained using 1H NMR spectroscopy although the stoichiometry was not accessed at neutral pH. Our results suggest that the spectroscopic observation of the YbPV complex can be used to conveniently measure concentrations of bisphosphonates down to 2-3 μM. 相似文献