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Cheok H.S.,Hanyang University | Jaworski J.,Hanyang University | Jaworski J.,Institute of Nanoscience and Technology
Biochemical Engineering Journal | Year: 2016

Formylglycine generating enzyme (FGE) is conserved through most organisms for the post-translational formation of aldehyde bearing formylglycine residues, often at sites possessing the general motif XCXPXRX. Using a library of the XCXPXRX repertoire displayed on the p3 protein coat of fd phage, we devised a phage screening strategy for identifying FGE substrates. Our methods of screening phage possessing possible substrates for enzymatic activity made use of the unique aldehyde residues produced on the substrate by reaction with FGE, which facilitated covalent capture of phage onto magnetic beads. This sequence dependent conversion/capture in conjunction with an unexpected sequence dependence of the enzymatic elution step used to liberate the phage for propagation served as the evolutionary selection pressures. The resulting HCTPRRP sequence identified from this phage screening procedure was an effective substrate for FGE, and through the course of the screening process it was selected for its propensity to be cleaved by trypsin. We anticipate this unique methodology for enzyme substrate screening may be applicable to selection of novel enzyme-substrate pairs by virtue of either sequence dependent immobilization or sequence dependent elution. © 2015 Elsevier B.V. Source

Kim J.Y.,Hanyang University | Jaworski J.,Hanyang University | Jaworski J.,Institute of Nanoscience and Technology
Macromolecular Research | Year: 2015

[Figure not available: see fulltext.] © 2015, The Polymer Society of Korea and Springer Sciene+Business Media Dordrecht. Source

Abraham S.,Banaras Hindu University | Srivastava S.,Banaras Hindu University | Kumar V.,Institute of Nanoscience and Technology | Pandey S.,Indian Institute of Technology BHU Varanasi | And 8 more authors.
Journal of Electroanalytical Chemistry | Year: 2015

The present work introduces partially reduced graphene oxide (pRGO)-silica (SiO2) particles hybrid system (pRGOSHs) for sensitive and cost effective free cholesterol detection. Fabricated out of thin layers of pRGOSHs, these proposed ChOx/pRGOSHs/ITO based biosensors have a detection range of 2.6-15.5 mM with an appreciable detection limit of 1.3 mM and sensitivity of 11.1 μA/mM/cm2. Low Michaelis-Menten constant (Km) (4.9 × 10- 4 mM) and high diffusivity constant (D) (3.2 × 10- 10 cm2/s) values clearly indicate enhanced immobilization of enzyme over the substrate. Additionally, electrochemical impedance studies indicate that the synergistic combination of SiO2 and pRGO also results in much lower impedance values (40% and 18% decrease in comparison to SiO2 and pRGO respectively) for an overall enhanced sensing performance. These results are further corroborated by the density functional theory based theoretical simulations indicating enhanced electron density (theoretically) in case of the proposed hybrid system. Finally, the present work also highlights the importance of Si-OH bonds formation in the proposed pRGOSHs composite system for attaining such enhanced biosensing ability. © 2015 Elsevier B.V. Source

Nirala N.R.,Banaras Hindu University | Abraham S.,Banaras Hindu University | Kumar V.,Banaras Hindu University | Kumar V.,Institute of Nanoscience and Technology | And 3 more authors.
Sensors and Actuators, B: Chemical | Year: 2015

In the present study, we report graphene quantum dots (GQDs), an enzyme mimetic of horse radish peroxidase (HRP), for unprecedented detection of free cholesterol. Synthesized directly from graphite using simple and quick one step wet chemical method, these GQDs in the presence of H2O2 exhibit highly efficient catalytic activity toward the oxidation of peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) to produce a blue colored product. The proposed detection system based on GQDs allows wide range (0.02-0.6 mM) of cholesterol sensing with a detection limit as low as 0.006 mM. Further, higher Vmax (7.3 × 10-6 M s-1) along with lower Km (0.01 mM) attest enhanced peroxidase like catalytic activity and better binding affinity of cholesterol oxidase (ChOx) to cholesterol resulting in good biosensor stability and resistance to environmental interferences. The proposed method without the use of sophisticated instruments perceives the cholesterol using naked eye with blue color compound formation. The potential of the method to be applied on field is shown by the proposed cholesterol measuring color wheel, where the shades of color are related to actual levels of cholesterol in the sample. © 2015 Published by Elsevier B.V. Source

Singh K.P.,Allahabad University | Singh M.K.,Allahabad University | Singh M.,Institute of Nanoscience and Technology
International Journal of Developmental Neuroscience | Year: 2016

A tremendous increase has been documented in the recent past in prescribing second generation atypical antipsychotic drugs (AAPDs) to the pregnant women with psychosis, considering their reproductive and teratogenic safety. Among AAPDs, risperidone (RIS) ranked third after olanzapine (OLZ) and quetiapine (QUE) used during pregnancy, as OLZ is associated to substantial weight gain in adults and offspring. Although teratogenic safety of RIS has been established, its potential role in developmental neurotoxicity and related neurobehavioral impairments in adolescents has not been documented so far. Therefore, present study has been undertaken to elucidate the effect of prenatal exposure to risperidone (RIS) on developmental neurotoxicity and apoptotic neurodegeneration in neocortical region of fetal brain; and related functional sequelae in young rat offspring. The pregnant Wistar rats were exposed to RIS at 0.8, 1.0 and 2.0 mg/kg, at equivalent therapeutic doses, orally from GD 6 to 21. Half of the pregnant rats were sacrificed and their brains were collected, weighed, and processed for neurohistopathological and apoptotic neurodegenerative evaluation. The remaining dams were allowed to deliver naturally, and their offspring were reared up to 10 weeks for neurobehavioral study. Prenatal exposure to RIS induced significant stunting of fetal body and brain weight, substantial reduction in the thickness of neocortical layers and apoptotic neurodegeneration in fetal brains, and delayed postnatal development and growth of the offspring; as well as long- lasting impact on anxiety like impaired behavioral responses on explorative mazes. Therefore, health care providers should be careful in prescribing atypical antipsychotics in general and RIS in particular, to the pregnant psychotic population. © 2016 ISDN. Source

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