Studies on pH and thermal deactivation of pectolytic enzymes from Aspergillus niger
TL;DR: The addition of protein doubled the half-life times of partially purified PMG, PG I and PG II and the interaction effect of pectolytic enzymes on deactivation was found to be significant.
About: This article is published in Biochemical Engineering Journal.The article was published on 2003-10-01. It has received 108 citations till now.
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TL;DR: The use of a cyclodextrin induced inclusion complex can be very useful during the bio-hydrolysis of poorly soluble substrates as mentioned in this paper, and it has been shown that the water solubility of styrene oxide (SO) was increased sevenfold (from 2.12 to 15.11g/l at 15°C) (20%, w/v).
15 citations
TL;DR: In this paper, isothermal titration calorimetry (ITC), circular dichroism (CD) spectroscopy, fluorescence spectra and dynamic light scattering were utilized to investigate the molecular interactions between human insulin and EGCG.
15 citations
TL;DR: The results demonstrated the feasibility of the new method to fabricate a new multienzyme system onto magnetic nanoparticles via covalent bonds to produce l-AHG, the first report where two different agarases were coimmobilized.
Abstract: Here we report a simple and efficient method to produce 3,6-anhydro-l-galactose (l-AHG) and agarotriose (AO3) in one step by a multienzyme system with the coimmobilized β-agarase AgWH50B and α-neoagarobiose hydrolase K134D. K134D was obtained by AgaWH117 mutagenesis and showed improved thermal stability when immobilized via covalent bonds on functionalized magnetic nanoparticles. The obtained multienzyme biocatalyst was characterized by Fourier transform infrared spectroscopy (FTIR). Compared with free agarases, the coimmobilized agarases exhibited a relatively higher agarose-to-l-AHG conversion efficiency. The yield of l-AHG obtained with the coimmobilized agarases was 40.6%, which was 6.5% higher than that obtained with free agarases. After eight cycles, the multienzyme biocatalyst still preserved 46.4% of the initial activity. To the best of our knowledge, this is the first report where two different agarases were coimmobilized. These results demonstrated the feasibility of the new method to fabricate ...
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TL;DR: It was found that pectinase from marine B. subtilis showed maximal activity in alkaline buffer at pH 9.0 and at 40°C, and that metal ions, namely, Mn2+ and Fe2+, stimulate pECTinase activity.
Abstract: Characterization, kinetic and thermodynamic parameters of purified pectinase from Bacillus subtilis, isolated from a marine sediment sample collected from Chinchani beach at Tarapore, India, were studied. Marine pectinase produced under submerged growth conditions was purified by ammonium sulfate precipitation followed by gel filtration chromatography using DEAE cellulose. Partial characterization of the marine pectinase was carried out in terms of effect of pH, temperature, substrate concentration, and metal ions. It was found that pectinase from marine B. subtilis showed maximal activity in alkaline buffer at pH 9.0 and at 40°C. It was also found that metal ions, namely, Mn(2+) and Fe(2+), stimulate pectinase activity. Marine pectinase followed Michaelis-Menten kinetics. The kinetics and thermodynamic parameters of the purified marine pectinase from B. subtilis were studied as the characterization of the enzyme is vital for its use in industrial processes.
14 citations
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...Negative values of entropy have also been reported during thermal deactivation of pectolytic enzymes from Aspergillus niger.([45]) The DG values calculated using Eq....
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TL;DR: In this paper, the effect of ionic liquids (ILs) based on non-nutritive sweeteners on the catalytic efficiency and the structural and thermal stability of lipases from Candida rugosa (CRL) and Rhizopus delemar (RhDL) was investigated.
Abstract: This is the first study on the effect of ionic liquids (ILs) based on non-nutritive sweeteners on the catalytic efficiency and the structural and the thermal stability of lipases from Candida rugosa (CRL) and Rhizopus delemar (RhDL). Initially, we synthesized two series of ILs, namely 1-akyl-3-methylimidazolium saccharinates {[CnC1im][Sac]} and 1-akyl-3-methylimidazolium acesulfamates {[CnC1im][Ace]}, where the alkyl substituent was butyl, hexyl, octyl or decyl. The activities of the two enzymes were tested in two hydrolytic reactions using walnut oil and 4-nitrophenyl acetate as substrates. The activity of CRL toward walnut oil was strongly influenced by the chain-length of the N-alkyl substituents at the imidazolium cation of the compounds. The ILs with short alkyl substituents (butyl or hexyl) activated moderately (up to 30%) or had no effect on CRL activity, while those with medium chain-length substituents strongly inhibited CRL. In the case of CRL, we observed the same behavior pattern for the two tested series of ILs, while for RhDL the same tendency was displayed only for the series of saccharinates. The coating of RhDL with 0.1 M [C8C1im][Sac] or [C8C1im][Ace] resulted in up to 1.5-fold increase in the enzyme initial activity. In contrast, CRL was strongly inhibited by these two ILs. We found that the effect of [C8C1im][Ace] on enzyme activity adopted concentration- and time-dependent manner for the two lipases. We observed a moderate increase in hydrolytic activity (by 1.2-fold factor) and good storage stability of RhDL (more than 30 days at 25 °C) when small quantities of all ionic liquids ( 4 C 1 im][Sac] or [C 4 C 1 im][Ace], CRL was also stabilized and its activity was preserved for more than 25 days at room temperature. For comparison, the activities of the stored at 25 °C non-treated with ILs soluble CRL and RhDL were reduced by half for 7 days and 5 days, respectively. In contrast, we observed rapid inactivation at higher temperatures for all ionic liquid-coated enzymes. For example, half-lives of 25 min and 57.3 min at 50 °C were estimated for the pre-treated with [C 4 C 1 im][Ace]-CRL and for the non-treated-CRL, respectively. In addition, applying Fourier transform infrared spectroscopy, we monitored the changes in the secondary structure of the two enzymes in presence of the tested ILs which explained the altered stability and the activities of the two enzymes. Interestingly, coating with small amounts of ILs prevents aggregation of the two lipases even at high protein concentration.
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TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
289,852 citations
TL;DR: In this paper, the probability of the activated state is calculated using ordinary statistical mechanics, and the probability multiplied by the rate of decomposition gives the specific rate of reaction, and necessary conditions for general statistical treatment to reduce to the usual kinetic treatment are given.
Abstract: The calculation of absolute reaction rates is formulated in terms of quantities which are available from the potential surfaces which can be constructed at the present time. The probability of the activated state is calculated using ordinary statistical mechanics. This probability multiplied by the rate of decomposition gives the specific rate of reaction. The occurrence of quantized vibrations in the activated complex, in degrees of freedom which are unquantized in the original molecules, leads to relative reaction rates for isotopes quite different from the rates predicted using simple kinetic theory. The necessary conditions for the general statistical treatment to reduce to the usual kinetic treatment are given.
4,718 citations
TL;DR: This review discusses various types of pectinases and their applications in the commercial sector.
1,001 citations