Silver nanoparticles (AgNPs) are best known for its catalytic activity. With the current knowledge of biophysics and spectroscopy techniques, we have attempted to study the changes in the structure of amylase upon interaction with AgNPs. Alpha-amylase interacted with AgNPs were investigated by UV-visible, Fourier transform infrared (FTIR), fluorescence and circular dichroism (CD) spectroscopic techniques. UV-Vis spectra showed a plasmon shift towards the lower wavelength indicating structural changes with increased solvent exposure to Trp residues. FTIR studies revealed Ag O bond formation via Trp residues. Fluorescence spectral intensity pertaining to Tryptophan (Trp) residue decreased with an increase in AgNP concentration and a hypsochromic shift from 0.6 mM AgNP. The content of α-helix was decreased by 26.87% while the turns were increased by 49.5% as analyzed by CD studies. The enzyme activity of AgNP-amylase was assayed by Nelson-Somogyi method. AgNP-amylase showed higher catalytic activity with 10 times higher production of reducing sugars at a concentration of 0.6 mM AgNP within fifteen minutes. The conformational change in the structure of amylase had a potential for the higher enzymatic activity for starch breakdown. These studies revealed that the protein structure had changes from UV-Vis, FTIR, CD and fluorescence spectroscopy which helped in increasing the enzyme activity. Copyright © 2013 American Scientific Publishers. All rights reserved.

Chandra Sekaran N

Centre for Nanobiotechnology

Vellore Campus

Amitava Mukherjee

Ernest V

Nirmala M.J

Gajalakshmi S

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Journal of Bionanoscience

CONTEXT: The conjugation of silver nanoparticles (AgNPs) with biomolecules such as oligosaccharides, DNA, proteins has attracted great attention of scientists recently. OBJECTIVE: In this study, lysozyme-AgNP conjugates were evaluated for its synergic antimicrobial effect. MATERIALS AND METHODS: AgNPs were synthesized and characterized using UV-Visible, X-ray diffraction analysis (XRD) and atomic force microscopy (AFM). AgNP (0-1 mM) was interacted with lysozyme for multi-spectrophotometric studies. Lysozyme was immobilized on AgNP at different ratios and the resulting nano-bio-conjugate was tested against Escherichia coli for potent synergic antibacterial effects. RESULTS AND DISCUSSION: A surface plasmon peak at 420 nm confirmed the presence of AgNPs and spherical to oval-shaped AgNPs were observed by AFM. The particle size was calculated to be 25 nm by XRD analysis. The maximum immobilization efficiency (98%) was achieved at 0.01:1 ratio of enzyme:AgNP. UV-Visible and fluorescence spectral studies revealed the binding of AgNPs to lysozyme by the formation of ground-state complex and the binding parameters were calculated. Circular dichroism studies confirmed decrease by 11% in the α-helical and 29.32% in β-sheets of lysozyme upon AgNP interaction. FTIR spectra revealed the binding of AgNP through thiol (-SH) linkages of lysozyme. Our results showed that the antimicrobial activity of lysozyme-AgNP conjugate was enhanced up to 86% decrease in the cell growth. CONCLUSION: In summary, the immobilization of lysozyme on AgNP has yielded a nano-bio-conjugate with synergistic antibacterial properties.

Artificial Cells, Nanomedicine, and Biotechnology

Enhanced activity of lysozyme-AgNP conjugate with synergic antibacterial effect without damaging the catalytic site of lysozyme

Functionalizing silver nanoparticles (AgNPs) with biomolecules have a number of applications in catalysis, sensing, pharmaceutics and therapy. For the first time, herein we report the interaction of amylase-AgNPs through various spectroscopic techniques. AgNPs are synthesized and characterized by UV-vis spectroscopy, transmission electron microscopy (TEM) and Dynamic Light Scattering (DLS). The binding of AgNPs to α-amylase are investigated by UV-vis, fluorescence, circular dichroism and FTIR spectroscopic techniques. Absorption intensity and Stern-Volmer plots confirmed the formation of the ground state complex with AgNPs. The quenching of the intrinsic protein fluorescence in the presence of different concentrations of AgNP was observed. The apparent binding constant (K) and number of binding sites (n) was calculated from the Stern-Volmer plot was found to be 4.92×103, 3.8×103 and 1.57, 1.3 for porcine pancreas and Bacillus subtilis α-amylase, respectively. Far-UV CD studies revealed the characteristic dichoric band at 222 nm for α-helical structure was shifted to 215 nm in porcine pancreatic α-amylase upon AgNP binding. Further, structural conformation change with peak shifts and the possible binding residues was confirmed through FTIR spectroscopy. © 2013 Elsevier B.V. All rights reserved.

Journal of Luminescence

Studies on the effect of AgNP binding on α-amylase structure of porcine pancreas and Bacillus subtilis by multi-spectroscopic methods

Silver nanoparticles (AgNPs) are proven to be an effective catalytic material for various applications due to their excellent optical and electronic properties. In this paper, we describe a novel approach for the degradation of starch using the catalytic behaviour of AgNPs in an enzyme catalysed reaction of starch hydrolysis by α-amylase. AgNPs were synthesized by soluble starch reducing silver nitrate to silver atoms. An increase of 4.7-fold in reducing sugar formation and 1.5 times faster enzyme activity confirmed the catalytic activity of AgNPs as a nanocatalyst. Surprisingly, starch degradation tests revealed that 9.9 mg of starch was hydrolysed within 5 min, which corroborates with the reducing sugar assay. In short, the present study paves way for the faster degradation of starch by immobilizing the enzyme onto the surface of the AgNP, which could be a promising application in the food industry. © 2012 Elsevier Ltd. All rights reserved.

Carbohydrate Research

Silver nanoparticles: a potential nanocatalyst for the rapid degradation of starch hydrolysis by α-amylase

Toxicology and Industrial Health

Differential propensity of citrate- and polyethylene glycol-coated silver nanoparticles to bovine hemoglobin

Colloids and Surfaces B: Biointerfaces

Systematic investigation on the interaction of bovine serum albumin with ZnO nanoparticles using fluorescence spectroscopy

Encyclopedia of Metalloproteins

Colloidal Silver Nanoparticles and Bovine Serum Albumin

PLoS ONE

Low Concentration of Silver Nanoparticles Not Only Enhances the Activity of Horseradish Peroxidase but Alter the Structure Also

Biophysical Investigation of α-Amylase Conjugated Silver Nanoparticles Proves Structural Changes Besides Increasing Its Enzyme Activity

Journal	Data powered by TypesetJournal of Bionanoscience
Publisher	Data powered by TypesetAmerican Scientific Publishers
ISSN	1557-7910
Open Access	0