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1.
Laura Del Coco Michael Assfalg Mariapina D’Onofrio Fabio Sallustio Francesco Pesce Francesco P. Fanizzi Francesco P. Schena 《Metabolomics : Official journal of the Metabolomic Society》2013,9(3):740-751
Immunoglobulin A nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide. Both one-dimensional NOESY and transverse-relaxation filter CPMG NMR spectra were recorded to investigate the urine metabolome of 24 IgAN patients and to detect altered metabolic profiles in comparison with 68 healthy matched controls. The spectral data were analyzed using multivariate statistical techniques. The analysis revealed that the NMR spectra of IgAN patients were statistically different from those of the controls (P = 4 × 10?7 for 1D-NOESY and P = 2 × 10?7 for CPMG). The robustness of the determined statistical model was confirmed by its predictive performance (for the 1D-NOESY dataset: sensitivity = 67 %, specificity = 95 %; for the CPMG dataset sensitivity = 60 %, specificity = 94 %). For the first time we found metabolites, including betaine and citrate, that are differentially modulated in IgAN patients compared to controls and that may be directly involved in the pathogenesis of IgAN. These metabolites may influence, directly or indirectly, the TNF-α, a regulating factor of the Th1/Th2 cell balance that is relevant in the pathology. The involvement of metabolites such as betaine and citrate in TNF-α regulation supports the power of the identified metabolic profiles to discern IgAN from controls. 相似文献
2.
Valerio Pieri Sonja Sturm Christoph Seger Chlodwig Franz Hermann Stuppner 《Metabolomics : Official journal of the Metabolomic Society》2012,8(2):335-346
The characterization of T. vulgaris plant material for quality control purposes was performed by NMR-based methods. Direct extraction of 141 T. vulgaris samples with DMSO-d
6 enabled the obtainment of crude extracts with a representative composition in terms of both volatile and non-volatile constituents.
The acquisition of 600 MHz 1H NMR spectra resulted in a dataset which was analyzed by a combination of metabolic profiling and target analysis approaches.
Preliminary analysis of the 1H NMR spectra was performed by principal component analysis, which revealed sample discrimination on a chemotype basis (thymol,
carvacrol and linalool chemotypes). Further minor discriminative constituents were identified as p-cymene, γ-terpinene, rosmarinic acid, and 3,4,3′,4′-tetrahydroxy-5,5′-diisopropyl-2,2′-dimethylbiphenyl. Metabolite identification
was accomplished by 1D and 2D NMR techniques and supported by spiking experiments. Fast dereplication of constituents not
available as reference compounds was performed by HPLC–SPE–NMR experiments. A targeted approach based on qHNMR was validated
for quantification of the identified secondary metabolites. Validation was performed in terms of precision (intra-day RSD ≤ 4.51%,
inter-day RSD ≤ 4.18%), repeatability (RSD ≤ 2.30%), accuracy (recovery rates within 93.4 and 103.4%), linearity (correlation
coefficients ≥ 0.9990), robustness, and stability. The amount of the dominant monoterpene in thymol, carvacrol, and linalool
chemotypes was respectively found to be within 0.4–2.6, 0.7–2.3, and 1.1–3.6% (w/w). Variable amounts of the precursors p-cymene and γ-terpinene were found in thymol and carvacrol chemotypes. The highest amount of rosmarinic acid and 3,4,3′,4′-tetrahydroxy-5,5′-diisopropyl-2,2′-dimethylbiphenyl
in the analyzed samples was respectively 4.6 and 0.4% (w/w). Since quantification is performed on a weight basis, the essential
oil content can be estimated based on the sum of the quantified monoterpenes. The NMR-based analysis of T. vulgaris represents a more comprehensive approach in comparison to traditional chromatographic methods such as GC and LC, respectively
employed for the analysis of volatile and non-volatile constituents. Further advantages lie in the simple sample preparation,
rapidity and reproducibility of the NMR analysis. 相似文献
3.
The depletion of protein signals in metabonomics analysis with the WET-CPMG pulse sequence 总被引:4,自引:0,他引:4
Van QN Chmurny GN Veenstra TD 《Biochemical and biophysical research communications》2003,301(4):952-959
Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool capable of providing a comprehensive metabolic profile of biofluids such as urine, plasma, and serum. Unfortunately, when measuring serum and plasma, the high protein concentration can obscure the signals originating from low molecular weight metabolites. We evaluated the use of different parameters within the Carr-Purcell-Meiboom-Gill (CPMG) pulse train of fast spin-echoes to remove the macromolecular signal contribution in one-dimensional proton (1H) NMR spectra. Experimental parameters such as the refocusing delay in the CPMG pulse train, pulse miscalibration, and recycle time were examined to assess the ability to remove the protein signals from the spectrum without causing a deleterious effect on the signals originating from free, low molecular weight metabolites. The 1H-NMR spectra of a variety of serum samples spiked with 2'-deoxyadenosine were acquired using various acquisition parameters. Our results show that the delay used in the CPMG spin-echo and the combination of the acquisition pulse flip angle and recycle time are the two major factors affecting the observed metabolite signal amplitudes in the resulting 1H-NMR spectrum. 相似文献
4.
James S. McKenzie Adrian J. Charlton James A. Donarski Alan D. MacNicoll Julie C. Wilson 《Metabolomics : Official journal of the Metabolomic Society》2010,6(4):574-582
A modified Lorentzian distribution function is used to model peaks in two-dimensional (2D) 1H–13C heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectra. The model fit is used to determine
accurate chemical shifts from genuine signals in complex metabolite mixtures such as blood. The algorithm can be used to extract
features from a set of spectra from different samples for exploratory metabolomics. First a reference spectrum is created
in which the peak intensities are given by the median value over all samples at each point in the 2D spectra so that 1H–13C correlations in any spectra are accounted for. The mathematical model provides a footprint for each peak in the reference
spectrum, which can be used to bin the 1H–13C correlations in each HSQC spectrum. The binned intensities are then used as variables in multivariate analyses and those
found to be discriminatory are rapidly identified by cross referencing the chemical shifts of the bins with a database of
13C and 1H chemical shift correlations from known metabolites. 相似文献
5.
Fourier transform infrared (FTIR) microspectroscopy can be considered to be a fast and non-invasive tool for distinguishing
between normal and cancerous cells and tissues without the need for laborious and invasive sampling procedures. Gastric samples
from four patients (age, 65±2 years) were analysed. Samples were obtained from the organs removed during gastrectomy and then
classified as normal or cancerous. Classification was based on histopathological examinations at our institution. Formalin-fixed
sections of gastric tissue were analysed by FTIR- microspectroscopy. To characterize differences between sections of normal
and cancerous tissue, specific regions of the spectra were analysed to study variations in the levels of metabolites. To distinguish
between two conditions (normal and cancerous), changes in the relative intensity of bands in the range 600–4000 cm−1 were analysed. A FTIR spectral map of the bands in the region 2800–3100 cm–1 and 900–1800 cm–1 were created to analyse pathological changes in tissues. The limited data available showed that normal gastric tissue had
stronger absorption than cancerous tissue over a wide region in the four patients. There was a significant decrease in total
biomolecular components for cancerous tissue compared with normal tissue. 相似文献
6.
Three-dimensional quantitative structure–activity relationship studies were performed on a series of 88 histamine receptor
4 (H4R) antagonists in an attempt to elucidate the 3D structural features required for activity. Several in silico modeling
approaches, including comparative molecular field analysis (CoMFA), comparative similarity indices analysis (CoMSIA), molecular
docking, and molecular dynamics (MD), were carried out. The results show that both the ligand-based CoMFA model (Q
2 = 0.548, R
ncv2 = 0.870, R
pre2 = 0.879, SEE = 0.410, SEP = 0.386) and the CoMSIA model (Q
2 = 0.526, R
ncv2 =0.866, R
pre2 = 0.848, SEE = 0.416, SEP = 0.413) are acceptable, as they show good predictive capabilities. Furthermore, a combined analysis
incorporating CoMFA, CoMSIA contour maps and MD results shows that (1) compounds with bulky or hydrophobic substituents at
positions 4–6 in ring A (R2 substituent), positively charged or hydrogen-bonding (HB) donor groups in the R1 substituent,
and hydrophilic or HB acceptor groups in ring C show enhanced biological activities, and (2) the key amino acids in the binding
pocket are TRP67, LEU71, ASP94, TYR95, PHE263 and GLN266. To our best knowledge, this work is the first to report the 3D-QSAR
modeling of these H4R antagonists. The conclusions of this work may lead to a better understanding of the mechanism of antagonism
and aid in the design of new, more potent H4R antagonists. 相似文献
7.
To identify the controls on dissolved organic carbon (DOC) production, we incubated soils from 18 sites, a mixture of 52 forest
floor and peats and 41 upper mineral soil samples, at three temperatures (3, 10, and 22°C) for over a year and measured DOC
concentration in the leachate and carbon dioxide (CO2) production from the samples. Concentrations of DOC in the leachate were in the range encountered in field soils (<2 to >50 mg l−1). There was a decline in DOC production during the incubation, with initial rates averaging 0.03–0.06 mg DOC g−1 soil C day−1, falling to averages of 0.01 mg g−1 soil C day−1; the rate of decline was not strongly related to temperature. Cumulative DOC production rates over the 395 days ranged from
less than 0.01 to 0.12 mg g−1 soil C day−1 (0.5–47.6 mg g−1 soil C), with an average of 0.021 mg g−1 soil C day−1 (8.2 mg g−1 soil C). DOC production rate was weakly related to temperature, equivalent to Q10 values of 0.9 to 1.2 for mineral samples and 1.2 to 1.9 for organic samples. Rates of DOC production in the organic samples
were correlated with cellulose (positively) and lignin (negatively) proportion in the organic matter, whereas in the mineral
samples C and nitrogen (N) provided positive correlations. The partitioning of C released into CO2–C and DOC showed a quotient (CO2–C:DOC) that varied widely among the samples, from 1 to 146. The regression coefficient of CO2–C:DOC production (log10 transformed) ranged from 0.3 to 0.7, all significantly less than 1. At high rates of DOC production, a smaller proportion
of CO2 is produced. The CO2–C:DOC quotient was dependent on incubation temperature: in the organic soil samples, the CO2–C:DOC quotient rose from an average of 6 at 3 to 16 at 22°C and in the mineral samples the rise was from 7 to 27. The CO2–C:DOC quotient was related to soil pH in the organic samples and C and N forms in the mineral samples. 相似文献
8.
Chemical Exchange Saturation Transfer (CEST) is an MRI approach that can indirectly detect exchange broadened protons that
are invisible in traditional NMR spectra. We modified the CEST pulse sequence for use on high-resolution spectrometers and
developed a quantitative approach for measuring exchange rates based upon CEST spectra. This new methodology was applied to
the rapidly exchanging Hδ1 and Hε2 protons of His57 in the catalytic triad of bovine chymotrypsinogen-A (bCT-A). CEST enabled
observation of Hε2 at neutral pH values, and also allowed measurement of solvent exchange rates for His57-Hδ1 and His57-Hε2
across a wide pH range (3–10). Hδ1 exchange was only dependent upon the charge state of the His57 (k
ex,Im+ = 470 s−1, k
ex,Im = 50 s−1), while Hε2 exchange was found to be catalyzed by hydroxide ion and phosphate base (
k\textOH - k_{{{\text{OH}}^{ - } }} = 1.7 × 1010 M−1 s−1,
k\textHPO42 - k_{{{\text{HPO}}_{4}^{2 - } }} = 1.7 × 106 M−1 s−1), reflecting its greater exposure to solute catalysts. Concomitant with the disappearance of the Hε2 signal as the pH was
increased above its pK
a, was the appearance of a novel signal (δ = 12 ppm), which we assigned to Hγ of the nearby Ser195 nucleophile, that is hydrogen bonded to Nε2 of neutral His57. The
chemical shift of Hγ is about 7 ppm downfield from a typical hydroxyl proton, suggesting a highly polarized O–Hγ bond. The
significant alkoxide character of Oγ indicates that Ser195 is preactivated for nucleophilic attack before substrate binding.
CEST should be generally useful for mechanistic investigations of many enzymes with labile protons involved in active site
chemistry. 相似文献
9.
Lindsay J. Sperling Andrew J. Nieuwkoop Andrew S. Lipton Deborah A. Berthold Chad M. Rienstra 《Journal of biomolecular NMR》2010,46(2):149-155
Magic-angle spinning (MAS) solid-state NMR (SSNMR) spectroscopy of uniformly-13C,15N labeled protein samples provides insight into atomic-resolution chemistry and structure. Data collection efficiency has
advanced remarkably in the last decade; however, the study of larger proteins is still challenged by relatively low resolution
in comparison to solution NMR. In this study, we present a systematic analysis of SSNMR protein spectra acquired at 11.7,
17.6 and 21.1 Tesla (1H frequencies of 500, 750, and 900 MHz). For two protein systems—GB1, a 6 kDa nanocrystalline protein and DsbA, a 21 kDa nanocrystalline
protein—line narrowing is demonstrated in all spectral regions with increasing field. Resolution enhancement is greatest in
the aliphatic region, including methine, methylene and methyl sites. The resolution for GB1 increases markedly as a function
of field, and for DsbA, resolution in the C–C region increases by 42%, according to the number of peaks that can be uniquely
picked and integrated in the 900 MHz spectra when compared to the 500 MHz spectra. Additionally, chemical exchange is uniquely
observed in the highest field spectra for at least two isoleucine Cδ1 sites in DsbA. These results further illustrate the
benefits of high-field MAS SSNMR spectroscopy for protein structural studies. 相似文献
10.
11.
Kyu-Bong Kim Myeon Woo Chung So Young Um Ji Seon Oh Seon Hwa Kim Mi Ae Na Hye Young Oh Wan-Seob Cho Ki Hwan Choi 《Metabolomics : Official journal of the Metabolomic Society》2008,4(4):377-392
The primary objective of this study was to discover biomarkers which are correlated with hepatotoxicity induced by chemicals
using 1H NMR spectral data of urine. A procedure of nuclear magnetic resonance (NMR) urinalysis using pattern recognition was proposed
for early screening of the hepatotoxicity of CCl4, acetaminophen (AAP), and d-galactosamine (GalN) in rats. The hepatotoxic compounds were expected to induce necrosis in hepatocytes. This was confirmed
through blood biochemistry and histopathology. CCl4 (1 ml/kg, po) or GalN (0.8 g/kg, ip) was single administered to Sprague–Dawley (S–D) rats and urine was collected every 24 h.
Animals were sacrificed 24 h or 48 h post-dosing. AAP (2 g/kg, po) was administered for 2 days and then the animals were sacrificed
24 h after the last treatment. NMR spectroscopy revealed evidently different clustering between control groups and hepatotoxicant
treatment groups in global metabolic profilings as indicated by partial least square (PLS)-discrimination analysis (DA). In
targeted profilings, endogenous metabolites of allantoin, citrate, taurine, 2-oxoglutarate, acetate, lactate, phenylacetyl
glycine, succinate, phenylacetate, 1-methylnicotinamide, hippurate, and benzoate were selected as putative biomarkers for
hepatoxicity by CCl4, AAP, and GalN. Comparison of our rat 1H NMR PLS-DA data with histopathological changes suggests that 1H NMR urinalysis can be used to predict hepatotoxicity induced by CCl4, AAP, and GalN. 相似文献
12.
Ahmed W Malik M Saeed I Khan AA Sadeque A Kaleem U Ahmed N Ajmal M Azam M Qamar R 《Molecular biology reports》2011,38(4):2541-2548
A case–control association study on 229 Myocardial Infarction (MI) patients and 217 healthy controls was carried out to determine
the role of tissue-plasminogen activator (t-PA) (Alu-repeat insertion (I)/deletion (D)) and plasminogen activator inhibitor
(PAI-1) (4G/5G insertion/deletion) polymorphisms with MI in the Pakistani population. In MI patients the genotype distribution
of the PAI-1 gene was not found to be different when compared with the unaffected controls (P > 0.05, χ2 = 1.03). The risk allele 4G was also not associated with MI (P > 0.05, χ2 = 0.46, odds ratio (OR) = 1.1 (95% confidence interval (CI) = 0.84–1.43), P > 0.05). Similarly, the genotype frequencies of t-PA I/I, I/D and D/D were not different from the unaffected controls (P > 0.05, χ2 = 1.60), and the risk allele “I” was not found to be associated with MI (P > 0.05, χ2 = 1.35, OR = 0.86 (95% CI = 0.66–1.11), P > 0.05). However, when the data were distributed along the lines of gender a significant association of the 4G/4G PAI-1 genotype
was observed with only the female MI patients (P < 0.05, z-test = 2.21). When the combined genotypes of both the polymorphisms were analyzed, a significant association of
MI was observed with the homozygous DD/4G4G genotype (P < 0.01, z-test = 2.61), which was specifically because of the female samples (P = 0.01, z-test = 2.53). In addition smoking (P < 0.001, χ2 = 13.52, OR = 3.45 (95% CI = 1.77–6.94)), diabetes (P < 0.001, χ2 = 22.45, OR = 8.89 (95% CI = 2.96–29.95)), hypertension (OR = 7.76 (95% CI = 2.88–22.68), P < 0.001) family history (P < 0.001, χ2 = 13.72, OR = 3.7 (95% CI = 1.71–8.18)) and lower HDL levels (P < 0.05) were found to be significantly associated with the disease. In conclusion the PAI-1 gene polymorphism was found to
have a gender specific role in the female MI patients. 相似文献
13.
The binding of palmatine to bovine serum albumin (BSA) was studied under physiological conditions (pH = 7.40) by molecular
spectroscopic approach. It was proved that the fluorescence quenching of BSA by palmatine is a result of the formation of
palmatine–BSA complex. Binding parameters were determined using the modified Stern–Volmer equation and Scatchard equation,
to measure the specific binding between palmatine and BSA. The thermodynamic parameters calculated, ∆G°, ∆H° and ∆S° indicate that the electrostatic interactions play a major role in the palmatine–BSA association. Site marker competitive
displacement experiments demonstrated that palmatine binds with specific affinity to site II (subdomain IIIA) of BSA. Furthermore,
the specific binding distance r (3.36 nm) was obtained according to fluorescence resonance energy transfer. The results of synchronous fluorescence spectra
and UV–Visible absorption spectra show that the conformation of bovine serum albumin has been changed. 相似文献
14.
Santhosh Acharya Ganesh Sanjeev N. N. Bhat K. Siddappa Y. Narayana 《Radiation and environmental biophysics》2009,48(2):197-203
The effect of electrons and gamma irradiation on the induction of micronuclei in cytokinesis-blocked human peripheral blood
lymphocytes was investigated to understand the relative biological effectiveness (RBE) of electrons compared with gamma rays.
Blood samples were irradiated with an 8 MeV pulsed electron beam, at a mean instantaneous dose rate of 2.6 × 105 Gy s−1. Gamma irradiation was carried out at a dose rate of 1.98 Gy min−1 using 60Co gamma source. A dose-dependent increase in micronuclei yield was observed. The dose–response relationships for induction
of micronuclei fitted well to a linear–quadratic relationship and the coefficients α and β of the dose–response curve were
estimated by fitting the data using error-weighted minimum χ
2 method. The RBE of 8 MeV electrons were found to be near unity as compared with gamma rays. 相似文献
15.
Vimaleswaran KS Radha V Ramya K Babu HN Savitha N Roopa V Monalisa D Deepa R Ghosh S Majumder PP Rao MR Mohan V 《Human genetics》2008,123(6):599-605
Adiponectin is an adipose tissue specific protein that is decreased in subjects with obesity and type 2 diabetes. The objective
of the present study was to examine whether variants in the regulatory regions of the adiponectin gene contribute to type
2 diabetes in Asian Indians. The study comprised of 2,000 normal glucose tolerant (NGT) and 2,000 type 2 diabetic, unrelated
subjects randomly selected from the Chennai Urban Rural Epidemiology Study (CURES), in southern India. Fasting serum adiponectin
levels were measured by radioimmunoassay. We identified two proximal promoter SNPs (−11377C→G and −11282T→C), one intronic
SNP (+10211T→G) and one exonic SNP (+45T→G) by SSCP and direct sequencing in a pilot study (n = 500). The +10211T→G SNP alone was genotyped using PCR-RFLP in 4,000 study subjects. Logistic regression analysis revealed
that subjects with TG genotype of +10211T→G had significantly higher risk for diabetes compared to TT genotype [Odds ratio
1.28; 95% Confidence Interval (CI) 1.07–1.54; P = 0.008]. However, no association with diabetes was observed with GG genotype (P = 0.22). Stratification of the study subjects based on BMI showed that the odds ratio for obesity for the TG genotype was
1.53 (95%CI 1.3–1.8; P < 10−7) and that for GG genotype, 2.10 (95% CI 1.3–3.3; P = 0.002). Among NGT subjects, the mean serum adiponectin levels were significantly lower among the GG (P = 0.007) and TG (P = 0.001) genotypes compared to TT genotype. Among Asian Indians there is an association of +10211T→G polymorphism in the
first intron of the adiponectin gene with type 2 diabetes, obesity and hypoadiponectinemia. 相似文献
16.
Ali Yilmaz Nils T. Nyberg Per Mølgaard Javad Asili Jerzy W. Jaroszewski 《Metabolomics : Official journal of the Metabolomic Society》2010,6(4):511-517
The aim of this study was to explore feasibility of 1H NMR metabolic fingerprinting for discrimination of authenticity of saffron using principal component analysis (PCA) modeling.
Authentic reference Iranian saffron (n = 31) and commercial samples (n = 32) were used. Cross-validated PCA models based on 1H NMR spectra of solutions prepared by direct extraction of grinded saffron with methanol-d
4 distinguished reference Iranian saffron samples from commercial samples that formed several distinct clusters, some of which
represent falsified samples as confirmed by microscopic analysis. The production sites and drying conditions of the authentic
reference Iranian samples were not reflected in the current dataset. Picrocrocin and glycosyl esters of crocetin emerged as
the most important 1H NMR markers of authentic saffron by using statistical correlation spectroscopy. In conclusion, 1H NMR spectra of saffron extracts combined with pattern recognition by PCA provide immediate means of unsupervised classification
of saffron samples. 相似文献
17.
Metallothioneins are low molecular weight proteins composed of 61–68 amino acid residues, and are characterized by high cysteine
content with lack of aromatic amino acids. Because of their rich thiol content, Metallothioneins have crucial biological functions
including cell proliferation and apoptosis, homeostasis of essential metals, cellular free radical scavenging, and metal detoxification.
In this study, we examined metallothionein 2A isoform in 122 kidney tissues from autopsy cases and 186 blood samples from
volunteers and detected A → G single-nucleotide polymorphism in metallothionein 2A core promoter region of Turkish population.
The promoter region of metallothionein 2A was amplified with the PCR technique and the amplified oligonucleotides were digested
with BsgI restriction enzyme. The genotype frequencies of the single-nucleotide polymorphism in the societies’ metallothionein 2A
core promoter region were determined as follows: 87% homozygote typical, 12.3% heterozygote and 0.7% homozygote atypical genotype.
The allele frequencies were consistent with Hardy–Weinberg equilibrium (χ2 = 0.2719; P > 0.05). 相似文献
18.
A broad regional understanding of tropical forest leaf photosynthesis has long been a goal for tropical forest ecologists,
but it has remained elusive due to difficult canopy access and high species diversity. Here we develop an empirical model
to predict sunlit, light-saturated, tropical leaf photosynthesis using leaf and simulated canopy spectra. To develop this
model, we used partial least squares (PLS) analysis on three tropical forest datasets (159 species), two in Hawaii and one
at the biosphere 2 laboratory (B2L). For each species, we measured light-saturated photosynthesis (A), light and CO2 saturated photosynthesis (A
max), respiration (R), leaf transmittance and reflectance spectra (400–2,500 nm), leaf nitrogen, chlorophyll a and b, carotenoids, and leaf mass per area (LMA). The model best predicted A [r
2
= 0.74, root mean square error (RMSE) = 2.9 μmol m−2 s−1)] followed by R (r
2
= 0.48), and A
max (r
2
= 0.47). We combined leaf reflectance and transmittance with a canopy radiative transfer model to simulate top-of-canopy
reflectance and found that canopy spectra are a better predictor of A (RMSE = 2.5 ± 0.07 μmol m−2 s−1) than are leaf spectra. The results indicate the potential for this technique to be used with high-fidelity imaging spectrometers
to remotely sense tropical forest canopy photosynthesis. 相似文献
19.
Copper (II) complex of formulation [Cu–Phen–Tyr](H2O)](ClO4) (Phen = 1,10-phenanthroline, l-Tyr = l-tyrosine), has been prepared, and their induced DNA oxidative cleavage activity studied. The complex binds to DNA by intercalation,
as deduced from the absorption and fluorescence spectral data. Scatchard plots constructed from the absorption titration data
gave binding constant 2.44 × 104 M−1 of base pairs. Extensive hypochromism, broadening, and red shifts in the absorption spectra were observed. Upon binding to
DNA, the fluorescence from the DNA–ethidium bromide system was efficiently quenched by the copper (II) complex. Stern–Volmer
quenching constant 0.61 × 103 M−1 obtained from the linear quenching plots. [Cu–Phen–Tyr] complex efficiently cleave the supercoiled DNA to its nicked circular
form with gallic acid as biological reductant at appropriate complex concentration. The gallic acid as reductant could observably
improve copper (II) complex to DNA damage. The pseudo-Michaelis–Menten kinetic parameters (k
cat, K
M) were calculated to be 1.32 h−1 and 5.46 × 10−5 M for [Cu–Phen–Tyr] complex. Mechanistic studies reveal the involvement of superoxide anions and hydroxyl radical (HO·) as the reactive species under an aerobic medium. 相似文献
20.
In this paper, we proposed a new method for the determination of either human serum albumin (HSA) or 5-Aminosalicylic acid
(5-ASA) by synchronous fluorescence spectra and examined the interaction between them using the molecular modeling method
under simulative physiological conditions. The optimum conditions of synchronous fluorometric determination of HSA were investigated
and the method was successfully applied to the determination of 5-ASA added to serum, urine, and saliva samples. The linear
range of the determination of HSA and 5-ASA were 1.60 – 414 μg mL−1 and 0.76 –22.95 μg mL−1, the detection limits were 0.552 μg mL−1 and 0.38 μg mL−1, respectively. In addition, the effect of various common ions on the determination of HSA with 5-ASA was also discussed at
room temperature.
Figure The salicylic acid moiety is located within the binding pocket. The ring of 5-ASA was inserted in the hydrophobic cavity of
site I, and it is important to note that the residue ARG-218 and the trptophan residue of HSA (Trp214) are in close proximity
to the ring of 5-ASA suggesting the existence of hydrophobic interaction between them. 相似文献