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Sathyanarayana N Gummadi
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Sathyanarayana N Gummadi
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Sathyanarayana N Gummadi
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Gummadi, Satyanarayana N.
Gummadi, S. N.
Gummadi, Sathyanarayana N.
Gummadi, Sathyanaryana N.
Gummadi, Sathyanarayana Naidu
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153 results
Now showing 1 - 10 of 153
- PublicationAnalysis of kinetic data of pectinases with substrate inhibition(01-06-2003)
; Enzyme kinetics data play a vital role in the design of reactors and control of processes. In the present study, kinetic studies on pectinases were carried out. Partially purified polymethylgalacturonase (PMG) and polygalacturonase (PG) were the two pectinases studied. The plot of initial rate vs. initial substrate concentration did not follow the conventional Michaelis-Menten kinetics, but substrate inhibition was observed. For PMG, maximum rate was attained at an initial pectin concentration of 3 g/l, whereas maximum rate was attained when the initial substrate concentration of 2.5 g/l of polygalacturonic acid for PG I and PG II. The kinetic data were fitted to five different kinetic models to explain the substrate inhibition effect. Among the five models tested, the combined mechanism of protective diffusion limitation of both high and inhibitory substrate concentrations (semi-empirical model) explained the inhibition data with 96-99% confidence interval. - PublicationBiochemical evidence for energy-independent flippase activity in bovine epididymal sperm membranes: An insight into membrane biogenesis(01-09-2013)
;Rajasekharan, Archita ;Francis, Vincent GerardDuring the maturation process spermatozoa undergo a series of changes in their lateral and horizontal lipid profiles. However, lipid metabolism in spermatozoa is not clearly understood for two reasons: i) the mature spermatozoa are devoid of endoplasmic reticulum, which is the major site of phospholipid (PL) synthesis in somatic cells, and ii) studies have been superficial due to the difficulty in culturing spermatozoa. We hypothesize that spermatozoa contain biogenic membrane flippases since immense changes in lipids occur during spermatogenic differentiation. To test this, we isolated spermatozoa from bovine epididymides and reconstituted the detergent extract of sperm membranes into proteoliposomes. In vitro assays showed that proteoliposomes reconstituted with sperm membrane proteins exhibit ATP-independent flip-flop movement of phosphatidylcholine (PC), phosphatidylserine, and phosphatidylglycerol. Half-life time of PC flipping was found to be ∼3.2±1 min for whole sperm membrane, which otherwise would have taken ∼11-12 h in the absence of protein. Further biochemical studies confirm the flip-flop movement to be protein-mediated, based on its sensitivity to protease and protein-modifying reagents. To further determine the cellular localization of flippases, we isolated mitochondria of spermatozoa and checked for ATP-independent flippase activity. Interestingly, mitochondrial membranes showed flip-flop movement but were specific for PC with half-life time of ∼5±2 min. Our results also suggest that spermatozoa have different populations of flippases and that their localization within the cellular compartments depends on the type of PL synthesis. © 2013 Society for Reproduction and Fertility. - PublicationBiochemical and functional characterization of human phospholipid scramblase 4 (hPLSCR4)(01-10-2012)
;Francis, Vincent GerardHuman phospholipid scramblase 4 (hPLSCR4), an isoform of the scramblase family, is a type II single-pass transmembrane protein whose function remains unknown. To understand its role, recombinant hPLSCR4 was obtained by cloning the ORF into a pET28 a(+) vector and overexpressed in Escherichia coli. Functional assay showed that Ca2+, Mg2+, and Zn2+ activate hPLSCR4 and mediate scrambling activity independent of the phospholipid head group. Far-UV-CD and fl uorescence spectroscopy revealed that Ca2+ and Mg2+ binding induces conformation change in hPLSCR4, exposing hydrophobic patches of the protein, and Ca2+ has more affi nity than Mg2+ and Zn2+. Stains-all studies further confirm that hPLSCR4 is a Ca2+-binding protein. Point mutation (Asp 290→Ala) in hPLSCR4 decreased the Ca2+-binding affi nity as well as Tb3+ luminescence, suggesting residues of the predicted Ca2+-binding motif are involved in Ca2+ binding. Functional reconstitution with (Asp290→Ala) mutant led to ~50% and ~40% decrease in scramblase activity in the presence of Ca2+ and Mg2+, respectively. Copyright © 2011-2012 by Walter de Gruyter. - PublicationStructural analysis and antioxidative properties of mutan (water-insoluble glucan) and carboxymethyl mutan from Streptococcus mutans(01-10-2020)
;Boddapati, Sirisha ;Rai, RandhirStreptococcus mutans (MTCC 497) was grown anaerobically in acidic Brain heart infusion (BHI) medium with 15 % sucrose to produce cell-bound and extracellular water-insoluble polysaccharide mutan. Fourier transformed infrared (FTIR) and 13C NMR studies revealed a mixed linkage of α-1−3 and α-1–6 mutan with a production yield of 1.8 g/L. Mutan has a branched structure with a molecular weight (Mw) of 5654 Da. Water-insoluble mutan was carboxymethylated at 0.93 degrees of substitution. FTIR spectra with characteristic peaks at 1603 cm−1 and 1418 cm−1 due to symmetric and asymmetric vibrations of the COO- group confirmed carboxymethylation. Thermal gravimetric analysis showed that native mutan and carboxymethyl mutan exhibited higher thermal stability. Carboxymethylation enhanced solubility and antioxidative radical-scavenging activity. The in-vitro antioxidative radical scavenging analysis revealed 52 % and 47 % inhibition of DPPH and ABTS radicals. - PublicationIndustrially important carbohydrate degrading enzymes from yeasts: Pectinases, chitinases, and β-1,3-glucanases(01-12-2009)
; ;Sunil Kumar, D. ;Dash, Swati S.Sahu, Santosh KumarPolysaccharide degrading enzymes are hydrolytic enzymes, which have a lot of industrial potential and also play a crucial role in carbon recycling. Pectinases, chitinases and glucanases are the three major polysaccharide degrading enzymes found abundantly in nature and these enzymes are mainly produced by fungal strains. Production of these enzymes by yeasts is advantageous over fungi, because the former are easily amenable to genetic manipulations and time required for growth and production is less than that of the latter. Several yeasts belonging to Saccharomyces, Pichia, Rhodotorula and Cryptococcus produce extracellular pectinases, glucanases and chitinases. This chapter emphasizes on the biological significance of these enzymes, their production and their industrial applications. © 2009 Springer Netherlands. - PublicationPlant extract mediated synthesis enhanced the functional properties of silver ferrite nanoparticles over chemical mediated synthesis(01-06-2020)
;Muthukumar, Harshiny ;Palanirajan, Santosh Kumar ;Shanmugam, Manoj KumarIn this study, the antibacterial, antioxidant and cytotoxicity behaviour of silver ferrite nanoparticles (AgFeO2 NPs) synthesized through chemical and green routes were compared. Green synthesis (Bio) of AgFeO2 NPs were prepared by precipitation method using Amaranthus blitum leaves extract as a reducing agent. Chemical synthesis (Che) of AgFeO2 NPs was mediated by sodium borohydride as a reducing agent. [AgFeO2 (Bio)] NPs showed reduced size, better monodispersity and surface area compared to [AgFeO2 (Che)] NPs. The results showed that synthesized NPs have better antibacterial activity against E. coli than S. aureus. In addition, 250 μg of AgFeO2 (Bio) and (Che) NPs showed antioxidant efficiency of 98 and 86%. The results showed that [AgFeO2 (Bio)] NPs showed lower cytotoxicity [AgFeO2 (Che)] NPs against human human embryonic kidney (HEK 293) cells. These results suggest that [AgFeO2 (Bio)] NPs have improved physicochemical properties thereby they can be used as an effective biocatalytic material in biotechnology. - PublicationChemotaxis of Pseudomonas sp. to caffeine and related methylxanthines(01-04-2008)
;Dash, Swati Sucharita ;Sailaja, Nori SriPseudomonas sp. isolated from soil of coffee plantation area has been shown to degrade higher concentrations of caffeine (∼15 g l-1) by N-demethylation at a rate higher than what has been reported for any strain so far. This strain exhibits positive chemotaxis towards caffeine (1,3,7-trimethylxanthine) in swarm plate assay and modified capillary assay in a dose dependant manner. Related methylxanthines and xanthine also act as chemoattractants for the strain with the highest relative chemotactic response (RCR) seen for xanthine. Chemotaxis in Pseudomonas sp. is possibly plasmid mediated as indicated by positive chemotaxis of plasmid transformed E. coli DH5α. The chemotactic abilities of Pseudomonas sp. combined with higher rates of degradation of caffeine can be used in the development of strategies for biodecaffeination of caffeine containing wastes. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA. - PublicationOptimization of physical parameters for biodegradation of caffeine by Pseudomonas sp.: A statistical approach(01-01-2007)
;Dash, Swati SucharitaPseudomonas sp. NCIM 5235 capable of degrading high concentrations of caffeine has been previously isolated from the soil of coffee plantation area. The isolate was capable of degrading 6.4 gL-1 initial concentration of caffeine at a rate of 0.1 g L-1 h-1. In this study, the physical parameters viz., pH, temperature and shaking speed have been optimized using central composite design. The optimum values of pH, temperature and shaking speed were found to be 7.8, 28°C and 190 rpm, respectively. Under optimized condition of pH, temperature and shaking speed, the rate of degradation of caffeine has been enhanced from 0.18 to 0.29 g L-1 h-1 which is 1.6 fold higher than the normal rate. This is the first report on degradation of high concentration of caffeine at higher rates. Under optimal conditions, the strain has also been found to degrade caffeine at 15 g L-1 initial concentration efficiently within 48 h. This makes Pseudomonas sp. NCIM 5235 an attractive candidate for development of biodecaffeination strategies. © Academic Journals Inc., USA. - PublicationAn overview of mammalian and microbial hormone-sensitive lipases (lipolytic family IV): biochemical properties and industrial applications(01-01-2022)
;Nagaroor, VijayalakshmiIn mammals, hormone-sensitive lipase (EC 3.1.1.79) is an intracellular lipase that significantly regulates lipid metabolism. Mammalian HSL is more active towards diacylglycerol but lacks a lid covering the active site. Dyslipidemia, hepatic steatosis, cancer, and cancer-associated cachexia are symptoms of HSL pathophysiology. Certain microbial proteins show a sequence homologous to the catalytic domain of mammalian HSL, hence called microbial HSL. They possess a funnel-shaped substrate-binding pocket and restricted length of acyl chain esters, thus known as esterases. These enzymes have broad substrate specificities and are capable of stereo, regio, and enantioselective, making them attractive biocatalysts in a wide range of industrial applications in the production of flavors, pharmaceuticals, biosensors, and fine chemicals. This review will provide insight into mammalian and microbial HSLs, their sources, structural features related to substrate specificity, thermal stability, and their applications. - PublicationInactivation of antibiotic resistant bacteria and elimination of transforming ability of plasmid carrying single and dual drug resistance genes by electro-oxidation using Ti/Sb-SnO2/PbO2 anode(01-04-2023)
;Rathinavelu, Sasikaladevi ;Shanmugam, Manoj Kumar; Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are one of the major components of environmental antimicrobial resistance (AMR). Wastewater treatment plant is an important source and a contributor of AMR components in environment. The existing tertiary treatment technologies viz., chlorination, ultraviolet treatment and ozonation are not effective in ARB disinfection or ARG removal. Therefore, it is important to evaluate the potential of advanced wastewater treatment technologies in removing ARB and ARGs. In this study, the potential of Ti/Sb-SnO2/PbO2 anode in disinfecting single ARB (pUC19-ampR), dual ARB (pBR322-ampR and tetR), regrowth inhibition, removal of intracellular and extracellular ARGs and loss of transformation efficiency were evaluated. Upto 7 log (99.99 %) removal of single ARB (0.212 min−1) and dual ARB (0.185 min−1) was achieved in 40 min and 35 min, respectively at an applied current density 30 mA cm−2. Scanning electron microscopy images confirmed extensive and irreparable cell damages. Therefore, no re-growth was observed upto 30 days. Agarose gel electrophoresis and qubit analysis confirmed degradation of intracellular and extracellular genetic material. Upto ∼7.5 log (53.14 ± 1.23 %) of intracellular and ∼5.3 log (41.43 ± 0.89 %) of extracellular ampR (pUC19) reduction was observed. Similarly, reduction of intracellular ampR and tetR (pBR322) were ∼6.5 log (55.19 ± 0.92 %) and ∼7.5 log (64.89 ± 2.39 %). While, extracellular ampR and tetR (pBR322) were ∼4.1 log (41.85 ± 1.62 %) and ∼4.9 log (52.49 ± 1.35 %), respectively. Despite low ARG removal efficiency, complete loss of transformation ability of intracellular and extracellular pUC19 and pBR322 was observed. From the results, it is evident that electro-oxidation is effective in disinfecting both the ARB, removal of intracellular and extracellular ARGs. Therefore, EOP is proposed as an effective and promising tertiary treatment technology.