scholarly journals Preparation of Chitosan/Magnetic Porous Biochar as Support for Cellulase Immobilization by Using Glutaraldehyde

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2672
Author(s):  
Haodao Mo ◽  
Jianhui Qiu
Keyword(s):  
Alkali Activation ◽  
Covalent Bonds ◽  
Ph Values ◽  
Maximum Reaction ◽  
Carboxymethyl Cellulose Sodium ◽  
Optimum Ph ◽  
Potential Applications ◽  
Km Value ◽  
Immobilized Cellulase ◽  
Menten Constant

In this work, porous biochar was obtained from sugarcane bagasse by alkali activation and pyrolysis and then magnetized with γ-Fe2O3 by calcination. After functionalization with chitosan and activation with glutaraldehyde, the as-prepared chitosan/magnetic porous biochar served as a support to immobilize cellulase by covalent bonds. The immobilization amount of cellulase was 80.5 mg cellulase/g support at pH 5 and 25 °C for 12 h of immobilization. To determine the enzymatic properties, 1% carboxymethyl cellulose sodium (CMC) (dissolved in 0.1 M buffer) was considered as a substrate for hydrolysis at different pH values (3–7) and temperatures (30–70 °C) for 30 min. The results showed that the optimum pH and temperature of the free and immobilized cellulase did not change, which were pH 4 and 60 °C, respectively. The immobilized cellulase had a relatively high activity recovery of 73.0%. However, it also exhibited a higher Michaelis–Menten constant (Km) value and a slower maximum reaction velocity (Vmax) value compared to the free enzyme. In the reusability assay, the immobilized cellulase showed initial glucose productivity of 330.9 mg glucose/g CMC and remained at 86.0% after 10 uses. In conclusion, the chitosan/magnetic porous biochar has great potential applications as a support for enzyme immobilization.

scholarly journals Kinetics Properties of Polyphenol Oxidase in Hawthorn (Crataegus spp)

2014 ◽  
Vol 25 ◽  
pp. 29-38 ◽  
Author(s):  
Shahriar Saeidian
Keyword(s):  
Enzyme Activity ◽  
Polyphenol Oxidase ◽  
Thermal Inactivation ◽  
Kojic Acid ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Optimum Ph ◽  
Km Value ◽  
Ph Range ◽  
Menten Constant

Polyphenol oxidase (PPO) from hawthorn was extracted and partially purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. The activity of polyphenol oxidase was investigated in Crataegus spp. Spectrophotometric method was used to assay the enzyme activity and the kinetic constants - maximum enzyme velocity (Vmax) and Michealis - Menten constant (Km). Of the substrates tested, catechol was the best substrate for PPO with a Km value of 2.2 mM. The optimum pH for PPO activity was found to be 7. The enzyme showed high activity over a broad pH range of 4 - 8. The optimal pH and temperature for enzyme activity were found to be 7 and 40-45 °C, respectively. km value for hawthorn PPO is calculated 22 mM for catechol and 6.7 mM for pyrogallol and 9.7 mM for L-dopa. As can be seen, affinity of PPOs for various substrates varies widely. The enzyme showed a broad activity over a broad pH and temperature range. The thermal inactivation studies showed that the enzyme is heat resistant. The enzyme showed the highest activity toward pyrogallol and no activity toward tyrosine. Of the inhibitors tested, the most potent inhibitors were kojic acid, cysteine and glycine , respectively

scholarly journals Isolation and Partial Purification of Polyphenol Oxidase from Seed of Melon (Cucumeropsis edulis)

2020 ◽  
Vol 11 (2) ◽  
pp. 9085-9096
Keyword(s):  
Metal Ions ◽  
Polyphenol Oxidase ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Partial Purification ◽  
Inhibitory Effects ◽  
Optimum Ph ◽  
Km Value ◽  
Menten Constant ◽  
Diphenolase Activity

Polyphenol oxidase (PPO) from Cucumeropsis edulis was extracted and partially purified through (NH4)2SO4 precipitation, dialysis, and ion-exchange chromatography on DEAE-Sephadex-A50. The spectrophotometric method was used to assay the enzyme activity in C. edulis using L-DOPA as substrate, the physicochemical properties such as the effect of pH and temperature, substrate specificity, kinetic constants - maximum enzyme velocity (Vmax), and Michaelis - Menten constant (Km) for three substrates namely, L-Dopa catechol and tyrosine were determined. The effects of inhibitors and metal ions on PPO activity were also investigated. The optimum pH and temperature values were found to be pH 6.5 and 50 °C, and the inhibitory effects of inhibitors such as ascorbic acid, EDTA, SDS, and metal ions were enhanced positively with increased concentration except with divalent metals such as Cu2+, Fe2+, and Zn2+ reflecting an activating effect on C. edulis PPO. Moreover, the enzyme solution showed both monophenolase and diphenolase activity with L-DOPA having the highest Vmax/Km value. However, the data obtained in this research provided a theoretical basis for the prevention of enzymatic browning of C. edulis during processing.

In Vitro Diabetogenic Effect of Cadmium on Liver

2017 ◽  
Vol 8 (01) ◽  
Author(s):  
Agung Biworo ◽  
Dwi Rezki Amalia ◽  
Gratianus Billy Himawan ◽  
Lisda Rizky Amalia ◽  
Valentina Halim ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Liver Homogenate ◽  
Liver Cells ◽  
Male Rats ◽  
Glycogen Level ◽  
Liver Sample ◽  
Km Value ◽  
Cd Exposure ◽  
Menten Constant

The objectives of this study were to determine the effect of cadmium (Cd) on glucose metabolism disruption in liver cells homogenate in vitro. The glucose metabolism disruption was analyzed by measuring the level of liver glucose, glycogen and methylglyoxal (MG), and the activity of glucokinase activity. In this experiment, a liver sample was taken from male rats (Rattus novergicus). Samples then homogenized and divided into four groups with; C served as control which contains liver homogenate only; T1 which contains liver homogenate + 0.03 mg/l of cadmium sulphate (CdSO4); T2 which contains liver homogenate + 0.3 mg/l of CdSO4; and T3 which contains liver homogenate + 3 mg/l of CdSO4. After treatment, liver glucose, glycogen, and MG levels, and glucokinase activity were estimated. The activity of liver glucokinase was estimated by measuring the Michaelis-Menten constant (Km) value. The results revealed that Cd exposure could significantly increase glucose and MG levels, the Km value of glucokinase, and decreased the glycogen level in liver cells (P>0.05). These results indicated that Cd exposure induced the disruption of glucose metabolism in the liver.

Trans-sialidase Associated with Atherosclerosis: Defining the Identity of a Key Enzyme Involved in the Pathology

2019 ◽  
Vol 20 (9) ◽  
pp. 938-941
Author(s):  
Victor Y. Glanz ◽  
Veronika A. Myasoedova ◽  
Andrey V. Grechko ◽  
Alexander N. Orekhov
Keyword(s):  
Acid Metabolism ◽  
Research Subject ◽  
Disease Pathogenesis ◽  
Sialidase Activity ◽  
Ph Values ◽  
Ldl Particles ◽  
Optimum Ph ◽  
Key Enzyme ◽  
St6gal I

Atherosclerosis is associated with the increased trans-sialidase activity, which can be detected in the blood plasma of atherosclerosis patients. The likely involvement in the disease pathogenesis made this activity an interesting research subject and the enzyme that may perform such activity was isolated and characterized in terms of substrate specificity and enzymatic properties. It was found that the enzyme has distinct optimum pH values, and its activity was enhanced by the presence of Ca2+ ions. Most importantly, the enzyme was able to cause atherogenic modification of lowdensity lipoprotein (LDL) particles in vitro. However, the identity of the discovered enzyme remained to be defined. Currently, sialyltransferases, mainly ST6Gal I, are regarded as major contributors to sialic acid metabolism in human blood. In this mini-review, we discuss the possibility that atherosclerosis- associated trans-sialidase does, in fact, belong to the sialyltransferases family.

scholarly journals Critical importance of pH and collector type on the flotation of sphalerite and galena from a low-grade lead–zinc ore

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdolrahim Foroutan ◽  
Majid Abbas Zadeh Haji Abadi ◽  
Yaser Kianinia ◽  
Mahdi Ghadiri
Keyword(s):  
Iron Ore ◽  
Low Grade ◽  
Zinc Recovery ◽  
Flotation Process ◽  
Ph Values ◽  
Lead And Zinc ◽  
Optimum Ph ◽  
Iron And Zinc ◽  
Lead Zinc ◽  
Zinc Concentrate

AbstractCollector type and pulp pH play an important role in the lead–zinc ore flotation process. In the current study, the effect of pulp pH and the collector type parameters on the galena and sphalerite flotation from a complex lead–zinc–iron ore was investigated. The ethyl xanthate and Aero 3418 collectors were used for lead flotation and Aero 3477 and amyl xanthate for zinc flotation. It was found that maximum lead grade could be achieved by using Aero 3418 as collector at pH 8. Also, iron and zinc recoveries and grades were increased in the lead concentrate at lower pH which caused zinc recovery reduction in the zinc concentrate and decrease the lead grade concentrate. Furthermore, the results showed that the maximum zinc grade and recovery of 42.9% and 76.7% were achieved at pH 6 in the presence of Aero 3477 as collector. For both collectors at pH 5, Zinc recovery was increased around 2–3%; however, the iron recovery was also increased at this pH which reduced the zinc concentrate quality. Finally, pH 8 and pH 6 were selected as optimum pH values for lead and zinc flotation circuits, respectively.

scholarly journals The Effect of pH Stress on the Survival of Rhizobium Trifolii and Sinorhizobium Meliloti in Vitro

2013 ◽  
Vol 70 (2) ◽  
pp. 449-450
Author(s):  
Monica NISTE ◽  
Roxana VIDICAN ◽  
Ioan ROTAR ◽  
Rodica POP
Keyword(s):  
Sinorhizobium Meliloti ◽  
Agar Medium ◽  
Rhizobium Trifolii ◽  
Ph Values ◽  
Optimum Ph ◽  
Yeast Extract Mannitol ◽  
Rhizobial Species ◽  
The Impact ◽  
Different Soils

Nitrogen-fixing symbiotic bacteria known as rhizobia can exist in different soils and adapt to different environmental conditions. The aim of this study was to determine the impact of pH on the growth of Rhizobium trifolii and Sinorhizobium meliloti. Rhizobial species were isolated using yeast extract mannitol agar medium) in which the pH values were adjusted to 5.0, 6.0, 8.0 and 9.0 by adding HCl and NaOH. The optimum pH for rhizobia is neutral or slightly alkaline (pH 8) and they are more sensitive to acidity. Sinorhizobium meliloti developed better in an acid medium compared to Rhizobium trifolii.

Coagulation-Direct Filtration of Soft, Low Alkalinity Humic Waters

1999 ◽  
Vol 40 (9) ◽  
pp. 55-62 ◽  
Author(s):  
Bjørnar Eikebrokk
Keyword(s):  
Natural Organic Matter ◽  
Pilot Scale ◽  
Quality Parameters ◽  
Efficient Removal ◽  
Direct Filtration ◽  
Ph Values ◽  
Optimum Ph ◽  
Calcium Sources ◽  
Ph Conditions ◽  
Removal Efficiencies

Optimisation of coagulation-direct filtration processes with respect to efficient removal of humic substances, i.e. natural organic matter (NOM) has gained a lot of focus in many countries over the last years. This paper presents experimental results from pilot scale research studies aimed at optimising the coagulation-direct filtration process applied to soft and humic raw waters with low turbidity and alkalinity levels. Comprehensive tests of 3 types of raw waters with different NOM content, 5 types of coagulants, and 3 calcium sources for the purpose of corrosion control have been conducted. Removal efficiencies with respect to relevant water quality parameters are presented, with typical relationships between raw water NOM content, coagulant dose requirements and pH. Generally, when applying metal-based coagulants, residual metal concentration was the critical parameter regarding minimum coagulant dose requirements. Typical NOM removal efficiencies were in the range of 75-90% and 40-70% with respect to colour and organic carbon, respectively. Optimum pH conditions for the removal of NOM and/or residual metals do not always coincide with that of turbidity. The experiments also showed that poly-aluminium and ferric chlorides might have some benefits over alum in terms of dose requirements and range of optimum pH values, and that chitosan may be used for colour removal with good results.

Study on the Kinetics of Adsorption of Cadmium by Chitosan

2010 ◽  
Vol 160-162 ◽  
pp. 1804-1809
Author(s):  
Qiang Bi ◽  
Juan Qin Xue ◽  
Ying Juan Guo ◽  
Yu Jie Wang ◽  
Yun Feng Xue
Keyword(s):  
Kinetic Equations ◽  
Adsorption Kinetic ◽  
Maximum Adsorption Capacity ◽  
Kinetics Of Adsorption ◽  
Ph Values ◽  
Optimum Ph ◽  
Pseudo Second Order ◽  
Simulated Wastewater ◽  
Isotherm Equations ◽  
Kinetics Of

The adsorption of cadmium in simulated wastewater by chitosan was investigated. The influence of temperature, contact time and pH on adsorption efficiency of cadmium was examined. Some related mathematical models were used in the fitting of experimental data. The results showed that at room temperature, the optimum pH of adsorption is between 4 and 7. At lower pH values, a strong competition existed between cadmium ions and protons for sorption sites and the sorption efficiency was decreased. After 60 minutes the adsorption equilibrium can be achieved. Chitosan is very effective at removing cadmium with the maximum adsorption capacity is 112.05mg•g-1. The adsorption kinetic curves agree with the pseudo-second-order adsorption kinetic equations and the adsorption isotherms could be well described by Langmuir isotherm equations.

Bioremoval of textile dyes with different chemical structures by Aspergillus versicolor in molasses medium

2012 ◽  
Vol 66 (10) ◽  
pp. 2177-2184 ◽  
Author(s):  
Burcu Ertit Taştan ◽  
Sevgi Ertuğrul Karatay ◽  
Gönül Dönmez
Keyword(s):  
Chemical Oxygen Demand ◽  
Laccase Activity ◽  
Oxygen Demand ◽  
Aspergillus Versicolor ◽  
Cod Reduction ◽  
Chemical Structures ◽  
Ph Values ◽  
Optimum Ph ◽  
Aspergillus Sp

Bioremoval of 17 dyes with different chemical structures by Aspergillus versicolor was detected in this study. Maxilon Red GRL (MR-GRL), Everdirect Fast Black VSF (EFB-VSF) and Brillant Blue R (BB-R) were removed better by fungal mycelia. Optimum pH values were found as 6 for all three dyes. In further experiments in the highest dye concentrations tested in this study, 58.3, 100 and 49% removal yields and 14.8, 12.6, 9.0 qm values were found for MR-GRL, EFB-VSF and BB-R, respectively. Chemical oxygen demand (COD) reduction after seven days of incubation period and role of laccase activity of Aspergillus sp. were also investigated. COD reduction and laccase activities were 55.6% and 2.93 U/mL for MR-GRL, 90.7% and 3.0 U/mL for EFB-VSF and 69.0% and 1.79 U/mL for BB-R, respectively. According to these results A. versicolor deserves notable attention for removal of these dyes in wastewater effluents.

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