Browsing by Author "Nivedita Jaiswal"

Now showing 1 - 11 of 11

A highly efficient and thermostable α-amylase from soya bean seeds
(2010) Om Prakash; Nivedita Jaiswal
The α-amylase from soya bean seeds was purified by affinity precipitation, resulting in approx. 20-fold purification with approx. 84% recovery. The purified α-amylase had an optimum pH of 5.5, optimum temperature of 75 °C, Arrhenius energy of activation of 6.03 kcal/mol (1 kcal≈4.184 kJ) and a Km of 2.427 mg/ml (starch substrate). The enzyme had maximum substrate specificity for starch. Among the various metal ions tested, Co2+ and Mn2+ were found to be strong activators. The effect of thiol group modifying agents showed that the thiols of soya bean α-amylase are not directly involved in catalysis. The thermostability of the enzyme makes it suitable for starch liquefaction and the detergent industry respectively. © 2010 Portland Press Limited.
An organic solvent and surfactant stable α-amylase from soybean seeds
(Acta Biochimica Polonica, 2013) Nivedita Jaiswal; Om Prakash
An organic solvent and surfactant stable a-amylase was obtained from soybean seeds. The direct and indirect effect of various organic solvents (non-polar, polar protic, and polar aprotic) and surfactants on the activity and stability of free enzyme was determined. The enzyme showed a very high catalytic efficiency and stabilization against most of the organic solvents and surfactants tested, except for few. Those organic solvents and surfactants (like chloroform, dimethyl formamide, n-butanol, and Tween 20), which caused an inhibition in enzyme activity, were used to study their effects on immobilized enzyme. The inhibitory effect was found to be decreased in immobilized enzyme as compared to free enzyme indicating that immobilization imparted stability to the enzyme. Moreover, the possibility of reuse of the enzyme in the presence of the organic solvents and surfactants was increased upon immobilization. The stability of soybean a-amylase towards organic solvents and surfactants shows that it is a potential candidate for use in organic-solvent biocatalysis as well as in detergent industries.
Application of response surface methodology for the determination of optimum reaction conditions (Temperature and pH) for starch hydrolysis by α-amylase
(2011) Nivedita Jaiswal; Om Prakash; Mahe Talat; S.H. Hasan; Rajesh Kumar Pandey
α-amylase from soybean seeds was purified to apparent homogeneity by affinity precipitation via entrapment in alginate with 84% recovery and about 20-fold purification. The α-amylase activity and stability was characterized at various pH and temperature. Response Surface Methodology (RSM) using two-level-two-factor full factorial Central Composite Design (CCD) model was employed to optimize process parameters like pH and temperature which affects the kinetics of α-amylase catalyzed hydrolysis of starch. The results predicted by the design were found in good agreement (R2 = 97.85%) with the experimental results indicating the applicability of proposed model. The multiple regression Analysis and ANOVA showed the individual and cumulative effect of pH and temperature on enzyme activity indicating that the activity increased with the increase of pH unto 5.5 and temperature 75°C. Thus, the RSM was successful in determining the optimum reaction conditions for starch hydrolysis by α-amylase. © 2011 Academic Journals Inc.
Effect of metal ions, EDTA and sulfhydryl reagents on soybean amylase activity
(2011) Om Prakash; Nivedita Jaiswal; Rajesh Kumar Pandey
Effect of some metal ions, EDTA and sulfhydryl reagents on the activity of partially purified amylase (Sp. Activity 1213 U mg-1 protein) of soybean seeds were studied. Cobalt (II) and Manganese (II) exhibited marked activating effects on the activity, enhancing up to 200% of the initial activity at 2 mM concentration while Mercury (II) ions severely inhibited. Inhibition by mercury and activation by cobalt and manganese were concentration-dependent. However, other metal ions (K+, Ca2+ Mg2+ Al3+ Cu2+, Zn2+ and Fe3+) moderately increased the enzyme activity to a certain extent and then suppressed. Sodium, Cadmium and Nickel had no detectable influence on the activity. EDTA (12.5 mM) was found to be ineffective even for 1 h of incubation at 27°C suggesting that no metal ion is present in the enzyme. No marked inhibition of amylase activity with the sulfhydryl reagents was found. The stability of the enzyme to metal ions as well as EDTA suggests its promising potential for use in detergent industries. © 2011 Academic Journals Inc.
Erratum: α-Amylase: An ideal representative of thermostable enzymes (Applied Biochemistry and Biotechnology DOI: 10.1007/s12010-009-8735-4)
(2010) Om Prakash; Nivedita Jaiswal
[No abstract available]
Fluoride quantitation in aqueous solution by agarose immobilized pumpkin urease
(2011) Om Prakash; Rajesh K. Pandey; Mahe Talat; Nivedita Jaiswal
Soluble as well as agarose immobilized pumpkin urease was utilized for easy and rapid detection and quantitation of fluoride in aqueous solution. Pumpkin urease was immobilized in 1.5 % agarose leading to 74.2 % immobilization. Inhibition by both soluble and agarose immobilized enzyme revealed a clear dependence on concentration and time. In order to inhibit the activity completely in soluble enzyme, 45 mM fluoride was required while agarose immobilized enzyme required almost double the concentration of the inhibitor i.e., 80 mM. The inhibition caused by fluoride was noncompetitive with K i value of 3.9 and 2.3 mM. The significance of the observations is discussed. © 2011 Bentham Science Publishers.
Immobilization of a thermostable • -amylase on agarose and agar matrices and its application in starch stain removal
(2011) Om Prakash; Nivedita Jaiswal
The purified and thermostable • -amylase from soybean seeds was immobilized by entrapment on agarose and agar matrices and their catalytic properties were compared. The optimum pH of • -amylase immobilized on both matrices was 7.0. The 1% of agarose (w/v) and 4% of agar (w/v) yielded an optimum immobilization of about 75 and 77% respectively. The K m and V max values as determined from the GraphPad Prism Software was found to be 3.46 and 0.224 (for agarose) and 3.16 and 0.227 (for agar) respectively. The reusability of agarose and agar immobilized enzyme was found to be upto 5 cycles. The effect of thiol inhibitors and thiols on immobilized • -amylase had been investigated. The easy availability of the purified soybean • -amylase and the ease of its immobilization on matrices of low cost makes it suitable for further use in industrial applications. The application of the agarose and agar immobilized enzyme in removal of starch stain from clothes was assessed. © IDOSI Publications, 2011.
Immobilization of Soybean α-amylase on gelatin and its application as a detergent additive
(2011) Nivedita Jaiswal; Om Prakash
The detailed kinetic study of the immobilized enzyme is usually important and pertinent for the better management of the enzyme preparation. Therefore, the suitable comparison of the various kinetic parameters of the immobilized a-amylase (on gelatin) with that of the soluble enzyme has been conducted. The purified a-amylase was immobilized on gelatin using glutaraldehyde as an organic hardener with an optimum immobilization of 82.5% followed by characterization with respect to pH, temperature, substrate concentration, effect of thiols and thiol inhibitors. The optimum pH shifted from 5.5 to 7.0 i.e., towards the basic side upon immobilization. The optimum temperature of gelatin immobilized a-amylase was 85°C as compared to soluble enzyme (75°C) showing an improvement in thermal stability. A decrease in Michaelis constant, Km from 2.427 to 1.870 mg mL-1 upon immobilization was observed. An increase in activity with all the thiols was observed. No marked inhibition with the thiol inhibitors (similar to the soluble enzyme) is an indication of the fact that there are no free thiol or sulfhydryl groups in soybean α-amylase which are necessary for catalysis. The reutilization capacity of the immobilized enzyme was up to seven cycles. The potential utility of the gelatin immobilized enzyme in removal of starch stain from cloths by various commercially available detergents and sodium lauryl sulphate was tested. The immobilized a-amylase could be considered as a potential candidate for use as a cleaning additive in detergents in order to facilitate the removal of starch stains due to which it may find potential application in laundry detergents. © 2011 Academic Journals Inc.
α-Amylase immobilization on gelatin: Optimization of process variables
(Academy of Scientific Research and Technology, 2012) Nivedita Jaiswal; Om Prakash; Mahe Talat; S.H. Hasan; Rajesh Kumar Pandey
α-Amylase was extracted and purified from soybean seeds to apparent homogeneity by affinity precipitation. The homogeneous enzyme preparation was immobilized on gelatin matrix using glutaraldehyde as an organic hardener. Response surface methodology (RSM) and 3-level-3-factor Box-Behnken design was employed to evaluate the effects of immobilization parameters, such as gelatin concentration, glutaraldehyde concentration and hardening time on the activity of immobilized α-amylase. The results showed that 20% gelatin (w/v), 10% glutaraldehyde (v/v) and 1 h hardening time yielded an optimum immobilization of 82.5%. © 2012 Academy of Scientific Research and Technology.
α-Amylase Inhibition: Some Practical Considerations
(2010) Om Prakash; Nivedita Jaiswal
Enzyme inhibitors are important tools of nature for regulating t he activity of enzymes in case of emergency. Proteinaceous inhibitors are the best studied in this group. Comparatively less is known about the inhibitors of -amylase, which might be an attractive candidate having potentials in various fields, from the treatment of diabetes to crop protection. The area has benefited from the recent determination of structures of α-amylases, inhibitors and complexes. Besides, discussing various types of α-amylase inhibitors and their structural basis of inhibition, the biotechnological approaches for exploitation of its inhibitory function have been outlined in this minireview. © 2010 Bentham Science Publishers Ltd.
α-Amylase: An ideal representative of thermostable enzymes
(Humana Press, 2010) Om Prakash; Nivedita Jaiswal
The conditions prevailing in the industrial applications in which enzymes are used are rather extreme, especially with respect to temperature and pH. Therefore, there is a continuing demand to improve the stability of enzymes and to meet the requirements set by specific applications. In this respect, thermostable enzymes have been proposed to be industrially relevant. In this review, α-amylase, a well-established representative of thermostable enzymes, providing an attractive model for the investigation of the structural basis of thermostability of proteins, has been discussed. © 2009 Humana Press.