Kinetic Behaviour of Amylase According to pH: A New Perspective for Starch Hydrolysis Process

2020 ◽  
Vol 16 (2) ◽  
pp. 135-144
Author(s):  
Ravneet K. Grewal ◽  
Baldeep Kaur ◽  
Gagandeep Kaur
Keyword(s):  
Metal Ions ◽  
Competitive Inhibition ◽  
Deae Cellulose ◽  
Kinetic Studies ◽  
Cost Effective ◽  
Starch Hydrolysis ◽  
Divalent Metal Ions ◽  
Activity Data ◽  
Time Saving ◽  
Alkaline Conditions

Background: Amylases are the most widely used biocatalysts in starch saccharification and detergent industries. However, commercially available amylases have few limitations viz. limited activity at low or high pH and Ca2+ dependency. Objective: The quest for exploiting amylase for diverse applications to improve the industrial processes in terms of efficiency and feasibility led us to investigate the kinetics of amylase in the presence of metal ions as a function of pH. Methods: The crude extract from soil fungal isolate cultures is subjected to salt precipitation, dialysis and DEAE cellulose chromatography followed by amylase extraction and is incubated with divalent metal ions (i.e., Ca2+, Fe2+, Cu2+, and Hg2+); Michaelis-Menton constant (Km), and maximum reaction velocity (Vmax) are calculated by plotting the activity data obtained in the absence and presence of ions, as a function of substrate concentration in Lineweaver-Burk Plot. Results: Kinetic studies reveal that amylase is inhibited un-competitively at 5mM Cu2+ at pH 4.5 and 7.5, but non-competitively at pH 9.5. Non-competitive inhibition of amylase catalyzed starch hydrolysis is observed with 5mM Hg2+ at pH 9.5, which changes to mixed inhibition at pH 4.5 and 7.5. At pH 4.5, Ca2+ induces K- and V-type activation of amylase catalyzed starch hydrolysis; however, the enzyme has V-type activation at 7mM Ca2+ under alkaline conditions. Also, K- and V-type of activation of amylase is observed in the presence of 7mM Fe2+ at pH 4.5 and 9.5. Conclusion: These findings suggest that divalent ions modulation of amylase is pH dependent. Furthermore, a time-saving and cost-effective solution is proposed to overcome the challenges of the existing methodology of starch hydrolysis in starch and detergent industries.

Partial Purification and Some Properties of a Hydroxycinnamoyl Glucosyltransferase from Tomato Fruits

1980 ◽  
Vol 35 (11-12) ◽  
pp. 967-972 ◽  
Author(s):  
A. Fleuriet ◽  
J. J. Macheix ◽  
R. Suen ◽  
R. K. Ibrahim
Keyword(s):  
Ferulic Acid ◽  
Metal Ions ◽  
Deae Cellulose ◽  
Divalent Metal ◽  
Partial Purification ◽  
Divalent Metal Ions ◽  
Tomato Fruits ◽  
Ammonium Sulphate Precipitation ◽  
Sh Group ◽  
Cherry Tomatoes

A glucosyltransferase was isolated from immature “cherry” tomatoes and was partially purified (200-fold) by ammonium sulphate precipitation and successive chromatography on Sephadex G-100 and DEAE-cellulose columns. The enzyme utilised the free hydroxycinnamic acids and UDP-glucose in the formation of their respective glucosides (pH 8.0) and glucose esters (pH 7.0); but did not accept the CoA thiolesters of HCAs in the presence of glucose-1-phosphate. The constant glucoside/glucose ester ratio observed during purification suggests that both reactions are catalysed by the same enzyme. The Km values for ρ-coumaric, caffeic, ferulic and sinapic acids were 0.8, 1.5, 1.4 and 2.5 μᴍ, respectively. With ferulic acid as substrate, the Km value for UDPG was 10 μᴍ. The enzyme required an -SH group for activity and the reaction was strongly inhibited by EDTA, divalent metal ions and UDP.

Binding of Divalent Metal Ions to Calcium-Free Peroxidase: Thermodynamic and Kinetic Studies

2012 ◽  
Vol 9 (9) ◽  
pp. 1806-1822
Author(s):  
Kohdadad Nazari ◽  
Vahid Kelay ◽  
Ali Mahmoudi ◽  
Seyed Majid Hashemianzadeh
Keyword(s):  
Metal Ions ◽  
Kinetic Studies ◽  
Divalent Metal ◽  
Divalent Metal Ions

Interaction of divalent metal ions with the NADP+-malic enzyme from maize leaves

1991 ◽  
Vol 81 (4) ◽  
pp. 462-466 ◽  
Author(s):  
Maria Fabiana Drincovich ◽  
Alberto A. Iglesias ◽  
Carlos S. Andreo
Keyword(s):  
Metal Ions ◽  
Malic Enzyme ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Maize Leaves

A Highly Crystalline Anthracene-Based MOF-74 Series Featuring Electrical Conductivity and Luminescence

2019 ◽  
Author(s):  
Patricia Scheurle ◽  
Andre Mähringer ◽  
Andreas Jakowetz ◽  
Pouya Hosseini ◽  
Alexander Richter ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Metal Ions ◽  
Light Emission ◽  
Block Design ◽  
High Surface ◽  
Visible Spectrum ◽  
Building Blocks ◽  
Divalent Metal Ions ◽  
Conductivity Enhancement ◽  
Surface Areas

Recently, a small group of metal-organic frameworks (MOFs) has been discovered featuring substantial charge transport properties and electrical conductivity, hence promising to broaden the scope of potential MOF applications in fields such as batteries, fuel cells and supercapacitors. In combination with light emission, electroactive MOFs are intriguing candidates for chemical sensing and optoelectronic applications. Here, we incorporated anthracene-based building blocks into the MOF-74 topology with five different divalent metal ions, that is, Zn2+, Mg2+, Ni2+, Co2+ and Mn2+, resulting in a series of highly crystalline MOFs, coined ANMOF-74(M). This series of MOFs features substantial photoluminescence, with ANMOF-74(Zn) emitting across the whole visible spectrum. The materials moreover combine this photoluminescence with high surface areas and electrical conductivity. Compared to the original MOF-74 materials constructed from 2,5-dihydroxy terephthalic acid and the same metal ions Zn2+, Mg2+, Ni2+, Co2+ and Mn2+, we observed a conductivity enhancement of up to six orders of magnitude. Our results point towards the importance of building block design and the careful choice of the embedded MOF topology for obtaining materials with desired properties such as photoluminescence and electrical conductivity.

E-Voting Kepala Desa dan Modal Sosial

2019 ◽  
Vol 2 (6) ◽  
pp. 759
Author(s):  
Khaulah Afifah ◽  
Lala M Kolopaking ◽  
Zessy Ardinal Barlan
Keyword(s):  
Social Capital ◽  
Random Sampling ◽  
Qualitative Data ◽  
Sampling Technique ◽  
Cost Effective ◽  
Simple Random Sampling ◽  
Community Based ◽  
Time Saving ◽  
The Social ◽  
Voting System

Head of a village election with e-voting system is a new thing for community The success level of e-voting system can be reached by fulfil several principles in order to the implementation going effective and the result of the election can be accepted by all. The objectives of this research is to analyze the relation between the success level of e-voting system with social capital of the community. This research is carried out with the quantitative approach and supported by qualitative data. This research takes 60 respondents using simple random sampling technique. The results showed that the success level of e-voting has a correlation with the level of social capital of the community. Based on the field study, the social capital of the community is classified as high. The high social capital makes the implementation of e-voting successful and the success level is also high, because in the election ten years ago occurred a conflict. The community considers e-voting easier and more practical, cost effective and time-saving, and the results of e-voting are also reliable. A practical and fast of e-voting system can be a solution especially for “rural-urban” community who are busy or work outside the village.Keywords: E-voting, the success level of the system, social capital Pemilihan kepala desa dengan sistem e-voting merupakan hal yang baru bagi masyarakat. Keberhasilan penerapan sistem e-voting dilihat dari terpenuhinya beberapa prinsip agar penerapannya berlangsung efektif dan hasilnya dapat diterima oleh seluruh masyarakat. Penelitian ini bertujuan untuk menganalisis hubungan tingkat keberhasilan sistem e-voting dalam pemilihan kepala desa dengan tingkat modal sosial masyarakat. Bentuk penelitian ini adalah penelitian kuantitatif yang didukung oleh analisis data kualitatif. Penelitian ini mengambil enam puluh responden dengan teknik simple random sampling. Hasil penelitian menunjukkan bahwa tingkat keberhasilan e-voting memiliki hubungan dengan tingkat modal sosial masyarakat. Berdasarkan kajian di lapang, modal sosial masyarakat tergolong tinggi. Tingginya modal sosial tersebut membuat pelaksanaan e-voting berhasil dan tingkat keberhasilannya juga tergolong tinggi karena pada pemilihan sepuluh tahun silam sempat terjadi konflik. Masyarakat menganggap sistem evoting lebih mudah dan praktis, hemat dalam segi biaya dan waktu, serta hasil dari pemilihan juga dapat dipertanggungjawabkan. Sistem e-voting yang praktis dan cepat dapat menjadi solusi khususnya bagi masyarakat daerah “desa-kota” yang memiliki kesibukan atau pekerjaan di luar desa.Kata Kunci: E-voting, keberhasilan sistem, modal sosial. 

Efficient Preconcentration of Cu2+, Zn2+ and Fe3+ with an Agarose-Schiff Base Sorbent

2007 ◽  
Vol 72 (7) ◽  
pp. 908-916 ◽  
Author(s):  
Payman Hashemi ◽  
Hatam Hassanvand ◽  
Hossain Naeimi
Keyword(s):  
Schiff Base ◽  
Metal Ions ◽  
Metal Ion ◽  
Good Accuracy ◽  
Kinetic Studies ◽  
Sample Volume ◽  
Effects Of Ph ◽  
Glass Column ◽  
High Concentrations ◽  
Ph Range

Sorption and preconcentration of Cu2+, Zn2+ and Fe3+ on a salen-type Schiff base, 2,2'- [ethane-1,2-diylbis(nitrilomethylidyne)]bis(2-methylphenol), chemically immobilized on a highly crosslinked agarose support, were studied. Kinetic studies showed higher sorption rates of Cu2+ and Fe3+ in comparison with Zn2+. Half-times (t1/2) of 31, 106 and 58 s were obtained for sorption of Cu2+, Zn2+ and Fe3+ by the sorbent, respectively. Effects of pH, eluent concentration and volume, ionic strength, buffer concentration, sample volume and interferences on the recovery of the metal ions were investigated. A 5-ml portion of 0.4 M HCl solution was sufficient for quantitative elution of the metal ions from 0.5 ml of the sorbent packed in a 6.5 mm i.d. glass column. Quantitative recoveries were obtained in a pH range 5.5-6.5 for all the analytes. The volumes to be concentrated exceeding 500 ml, ionic strengths as high as 0.5 mol l-1, and acetate buffer concentrations up to 0.3 mol l-1 for Zn2+ and 0.4 mol l-1 for Cu2+ and Fe3+ did not have any significant effect on the recoveries. The system tolerated relatively high concentrations of diverse ions. Preconcentration factors up to 100 and detection limits of 0.31, 0.16 and 1.73 μg l-1 were obtained for Cu2+, Zn2+ and Fe3+, respectively, for their determination by a flame AAS instrument. The method was successfully applied to the metal ion determinations in several river water samples with good accuracy.

scholarly journals Chemical Modification of Combusted Coal Gangue for U(VI) Adsorption: Towards a Waste Control by Waste Strategy

2021 ◽  
Vol 13 (15) ◽  
pp. 8421
Author(s):  
Yuan Gao ◽  
Jiandong Huang ◽  
Meng Li ◽  
Zhongran Dai ◽  
Rongli Jiang ◽  
...  
Keyword(s):  
Structural Analysis ◽  
High Efficiency ◽  
Low Cost ◽  
Chemical Activation ◽  
Cost Effective ◽  
Coal Gangue ◽  
Order Kinetic ◽  
Practical Applications ◽  
Detailed Structural Analysis ◽  
Alkaline Conditions

Uranium mining waste causes serious radiation-related health and environmental problems. This has encouraged efforts toward U(VI) removal with low cost and high efficiency. Typical uranium adsorbents, such as polymers, geopolymers, zeolites, and MOFs, and their associated high costs limit their practical applications. In this regard, this work found that the natural combusted coal gangue (CCG) could be a potential precursor of cheap sorbents to eliminate U(VI). The removal efficiency was modulated by chemical activation under acid and alkaline conditions, obtaining HCG (CCG activated with HCl) and KCG (CCG activated with KOH), respectively. The detailed structural analysis uncovered that those natural mineral substances, including quartz and kaolinite, were the main components in CCG and HCG. One of the key findings was that kalsilite formed in KCG under a mild synthetic condition can conspicuous enhance the affinity towards U(VI). The best equilibrium adsorption capacity with KCG was observed to be 140 mg/g under pH 6 within 120 min, following a pseudo-second-order kinetic model. To understand the improved adsorption performance, an adsorption mechanism was proposed by evaluating the pH of uranyl solutions, adsorbent dosage, as well as contact time. Combining with the structural analysis, this revealed that the uranyl adsorption process was mainly governed by chemisorption. This study gave rise to a utilization approach for CCG to obtain cost-effective adsorbents and paved a novel way towards eliminating uranium by a waste control by waste strategy.

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