Development of a solid-phase extraction coupling chemiluminescent enzyme immunoassay for determination of organophosphorus pesticides in environmental water samples

Solid-phase extraction (SPE) and direct competitive chemiluminescence enzyme immunoassay (dcCL-EIA) were combined for the detection of organophosphorus pesticides (OPs) in environmental water samples. dcCL-EIA based on horseradish peroxidase labeled with a broad-specificity monoclonal antibody against OPs was developed, and the effects of several physicochemical parameters on dcCL-EIA performance were studied. SPE was used for the pretreatment of water samples to remove interfering substances and to concentrate the OP analytes. The coupling of SPE and dcCL-EIA can detect seven OPs (parathion, coumaphos, phoxim, quinalphos, triazophos, dichlofenthion, and azinphos-ethyl) with the limit of quantitation below 0.1 ng/mL. The recoveries of OPs from spiked water samples ranged from 62.5% to 131.7% by SPE-dcCL-EIA and 69.5% to 112.3% by SPE-HPLC-MS/MS. The screening of OP residues in real-world environmental water samples by the developed SPE-dcCL-EIA and their confirmatory analysis using SPE-HPLC-MS/MS demonstrated that the assay is ideally suited as a monitoring method for OP residues prior to chromatographic analysis.

Genetic variation in MME in relation to neprilysin protein and enzyme activity, Aβ levels, and Alzheimer's disease risk

Neprilysin (NEP), also known as membrane metalloendopeptidase (MME), is considered amongst the most important ß-amyloid (Aß)-degrading enzymes with regard to prevention of Alzheimer's disease (AD) pathology. Variation in the NEP gene (MME) has been suggested as a risk factor for AD. We conducted a genetic association study of 7MME SNPs - rs1836914, rs989692, rs9827586, rs6797911, rs61760379, rs3736187, rs701109 - with respect to AD risk in a cohort of 1057 probable and confirmed AD cases and 424 age-matched non-demented controls from the United Kingdom, Italy and Sweden. We also examined the association of these MME SNPs with NEP protein level and enzyme activity, and on biochemical measures of Aß accumulation in frontal cortex - levels of total soluble Aß, oligomeric Aß(1-42), and guanidine-extractable (insoluble) Aß - in a sub-group of AD and control cases with post-mortem brain tissue. On multivariate logistic regression analysis one of the MME variants (rs6797911) was associated with AD risk (P = 0.00052, Odds Ratio (O.R. = 1.40, 95% confidence interval (1.16-1.70)). None of the SNPs had any association with Aß levels; however, rs9827586 was significantly associated with NEP protein level (p=0.014) and enzyme activity (p=0.006). Association was also found between rs701109 and NEP protein level (p=0.026) and a marginally non-significant association was found for rs989692 (p=0.055). These data suggest that MME variation may be associated with AD risk but we have not found evidence that this is mediated through modification of NEP protein level or activity.

Novel hapten synthesis for antibody production and development of an enzyme-linked immunosorbent assay for determination of furaltadone metabolite 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ)

A heterologous competitive indirect enzyme-linked immunosorbent assay (ciELISA) for the determination of the furaltadone metabolite 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ) was developed. AMOZ was derivatised with 2-(4-formylphenoxy) acetic acid or 2-(3-formylphenoxy) acetic acid to obtain two novel immunizing haptens. The ability of these haptens in producing specific polyclonal antibodies against the nitrophenyl derivative of AMOZ (NPAMOZ) was compared with that of traditional immunizing haptens (derivatised AMOZ with 3-carboxybenzaldehyle or 4-carboxybenzaldehyle). The results indicated that the novel immunizing haptens were able to produce antibodies with almost a two-fold improvement in sensitivity of the ciELISA for NPAMOZ in comparison with the existing antibody based ELISAs. The differences in sensitivity were explained by the molecular modeling of the lowest energy conformations of NPAMOZ and the haptens. Another novel hapten, derivatised AMOZ with 2-oxoacetic acid, was synthesized and used as a heterologous coating hapten. The results showed that this strategy of using only a partial structure of the target molecule as the coating hapten was able to obtain a two to three-fold improvement in sensitivity. This study provided a modern approach for the development of an immunoassay with improved sensitivity for the metabolites of nitrofuran antibiotics. © 2012 Elsevier B.V. All rights reserved.

Controlled fragrance delivery in functionalised ionic liquid-enzyme systems

It is often believed that both ionic liquids and surfactants generally behave as non-specific denaturants of proteins. In this paper, it is shown that amphiphilic ionic liquids bearing a long alkyl chain and a target molecule, where the target molecule is appended via a carboxylic ester functionality, can represent super-substrates that enable the catalytic activity of an enzyme, even at high concentrations in solution. Menthol has been chosen as the target molecule for slow and controlled fragrance delivery, and it was found that the rate of the menthol release can be controlled by the chemical structure of the ionic liquid. At a more fundamental level, this study offers an insight into the complex hydrophobic, electrostatic, and hydrogen bond interactions between the enzyme and substrate.

Phase I and II biotransformation enzymes and polycyclic aromatic hydrocarbons in the Mediterranean mussel (Mytilus galloprovincialis, Lamarck, 1819) collected in front of an oil refinery

The aim of the present study was to investigate the responses of phase I and II biotransformation enzymes and levels of PAHs in the Mediterranean mussel (Mytilus galloprovincialis, Lamarck, 1819) collected from three sites at different distance from an oil refinery. Phase I enzyme activities as NAD(P)H-cyt c red, NADH ferry red, B(a)PMO and phase II as UDPGT. GST were measured in digestive gland while 16 PAHs (US-EPA) in whole soft tissue. An added value to the data obtained in the present study rely on the RDA analysis which showed close correlations between PAHs levels and phase I enzyme activities in mussels collected in front of the refinery. And again a significant spatial correlation between B(a)P levels and NADPH-cyt c red activities was observed using linear models. No differences among sites for B(a) PMO and phase II GST activities were observed, while the application of UDPGT as biomarkers requires further investigation. (C) 2012 Elsevier Ltd. All rights reserved.

Signal enhancement of surface plasmon resonance immunoassay using enzyme precipitation-functionalized gold nanoparticles: A femto molar level measurement of anti-glutamic acid decarboxylase antibody

Colloidal gold nanoparticles (AuNPs) and precipitation of an insoluble product formed by HRP-biocatalyzed oxidation of 3,3'-diaminobenzidine (DAB) in the presence of H2O2 were used to enhance the signal obtained from the surface plasmon resonance (SPR) biosensor. The AuNPs were synthesized and functionalized with HS-OEG(3)-COOH by self assembling technique. Thereafter, the HS-OEG3-COOH functionalized nanoparticles were covalently conjugated with horseradish peroxidase (HRP) and anti IgG antibody to form an enzyme-immunogold complex. Characterizations were performed by several methods: UV-vis absorption, DLS, HR-TEM and Fr-IR. The Au-anti IgG-HRP complex has been applied in enhancement of SPR immunoassay using a sensor chip constructed by 1:9 molar ratio of HS-OEG(6)-COOH and HS-OEG(3)-OH for detection of anti-GAD antibody. As a result, AuNPs showed their enhancement as being consistent with other previous studies while the enzyme precipitation using DAB substrate was applied for the first time and greatly amplified the SPR detection. The limit of detection was found as low as 0.03 ng/ml of anti-GAD antibody (or 200 fM) which is much higher than that of previous reports. This study indicates another way to enhance SPR measurement, and it is generally applicable to other SPR-based immunoassays.

Effects of Gold Nanoparticle and Enzyme Precipitation on Enhancement of Surface Plasmon Resonance Immunoassay: A Super Sensitive Measurement of Anti- Glutamic Acid Decarboxylase Antibody

Introduction: In this study, colloidal gold nanoparticle and precipitation of an insoluble product formed by HRP-biocatalyzed oxidation of 3,3'-diaminobenzidine (DAB) in the presence of H2O2 were used to enhance the signal obtained from the surface plasmon resonance biosensor.

Methods: The colloidal gold nanoparticle was synthesized as described by Turkevitch et al., and their surface was firstly functionalized with HS(CH2)11(OCH2CH2)3COOH (OEG3¬-COOH) by self assembling technique. Thereafter, those OEG3-COOH functionalized nanoparticles were covalently conjugated with horseradish peroxidase (HRP) and anti-IgG antibody (specific to the Fc portion of all human IgG subclasses) to form an enzyme-immunogold complex. Characterization was performed by several methods: UV-Vis absorption, dynamic light scattering (DLS), transmission electron microscopy (TEM) and FTIR. The as-prepared enzyme-immunogold complex has been applied in enhancement of SPR immunoassay. A sensor chip used in the experiment was constructed by using 1:10 molar ratio of HS(CH2)11(OCH2CH2)6COOH and HS(CH2)11(OCH2CH2)3OH. The capture protein, GAD65 (autoantigen) which is recognized by anti-GAD antibody (autoantibody) in the sera of insulin-dependent diabetes mellitus patients, was immobilized onto the 1:10 surface via biotin-streptavidin interaction.

Results and conclusions: In the research, we reported the influences of gold nanoparticle and enzyme precipitation on the enhancement of SPR signal. Gold nanoparticle showed its enhancement as being consistent with other previous studies, while the enzyme precipitation using DAB substrate was applied for the first time and greatly amplified the SPR detection. As the results, anti-GAD antibody could be detected at pg/ml level which is far higher than that of commercial ELISA detection kit. This study indicates another way to enhance SPR measurement, and it is generally applicable to other SPR-based immunoassays.

Strawberries, Blueberries, and Cranberries in the Metabolic Syndrome:Clinical Perspectives

Emerging science supports therapeutic roles of strawberries, blueberries, and cranberries in metabolic syndrome, a prediabetic state characterized by several cardiovascular risk factors. Interventional studies reported by our group and others have demonstrated the following effects: strawberries lowering total and LDL-cholesterol, but not triglycerides, and decreasing surrogate biomarkers of atherosclerosis (malondialdehyde and adhesion molecules); blueberries lowering systolic and diastolic blood pressure and lipid oxidation and improving insulin resistance; and low-calorie cranberry juice selectively decreasing biomarkers of lipid oxidation (oxidized LDL) and inflammation (adhesion molecules) in metabolic syndrome. Mechanistic studies further explain these observations as up-regulation of endothelial nitric oxide synthase activity, reduction in renal oxidative damage, and inhibition of the activity of carbohydrate digestive enzymes or angiotensin-converting enzyme by these berries. These findings need confirmation in future studies with a focus on the effects of strawberry, blueberry, or cranberry intervention in clinical biomarkers and molecular mechanisms underlying the metabolic syndrome.

Mammalian triokinase and dihydroxyacetone kinase are the same enzyme

It is widely accepted that the ATP-dependent phosphorylation of D-glyceraldehyde in the fructokinase pathway of fructose metabolism requires the enzyme “triokinase”. However, experimental data on this enzyme are remarkably scarce. The enzyme has been purified from a variety of sources and peptides derived from the pig kidney enzyme show high similarity to human dihydroxyacetone kinase – an enzyme which also has FMN cyclase activity in high manganese ion concentrations. The properties of the two enzymes are also highly similar. Therefore it is proposed that mammalian triokinase and dihydroxyacetone kinase are, in fact, the same enzyme. This has consequences for investigations of normal and aberrant fructose metabolism and for the teaching of biochemistry in medical and science courses.

Use of immunosorbent-purified antigens of Fasciola hepatica in enzyme immunoassays

A monoclonal antibody specific for the T1 tegumental antigen of Fasciola hepatica was used as a solid-phase immunosorbent for the purification of T1 antigen from homogenised mature F hepatica. Material fractionated by this technique was successfully used in enzyme-linked immunoassays to detect antibodies to F hepatica in sera from sheep and cattle. Species differences in response to infection by F hepatica were demonstrated.

An assay for angiotensin-converting enzyme using capillary zone electrophoresis

A sensitive and rapid method was developed for angiotensin-converting enzyme (ACE) activity determination by capillary zone electrophoresis. Hippuryl-View the MathML source-histidyl-View the MathML source-leucine, a synthetic tripeptide, was used as the ACE-specific substrate. Capillary zone electrophoresis was employed to separate the products of the enzymatic reaction and the ACE activity was determined by quantification of hippuric acid, a result of the enzymatic reaction on the tripeptide. The capillary electrophoresis was performed in a 27 cm × 75 μm i.d. fused-silica capillary using 200 mM boric acid–borate buffer (pH 9.0) as a run buffer with an applied voltage of 8.1 kV at a capillary temperature of 23°C. The electrophoresis was monitored at 228 nm. Each electrophoretic run requires only a nanoliter of the enzymatic reactant solution, at only 6 min, rendering a powerful tool for the ACE assay.