Showing 5 results for Metal Ions
Reza Hassan Sajedi, , Khosro Khajeh,
Volume 4, Issue 1 (10-2013)
Abstract
Maltogenic Amylases (MAase) are a subfamily of Į-amylase family that can hydrolyze multiple substrates including starch, pullulan and cyclodextrins however, they prefer cyclodextrins to others, and unlike other Į-amylases, they are intracellular. This enzyme has the potential for use in many industrial processes such as food, fermentation and pharmacy. The effect of different concentrations of Ca2+ and K+ ions on irreversible thermoinactivation of the enzyme at 65 ÛC showed that Ca2+ and K+ decreased and increased its thermal stability. The CD spectra of the enzyme in the presence and absence of metal ions were measured to detect changes in the secondary structure contents. The spectra showed a decrease in the Į-helix content in the presence of 1 and 10 mM of Ca2+, but in the presence of 5 mM, a drastic increase in Į-helix content of the enzyme was witnessed. In the presence of 1 and 5 mM of Na+ the Į-helix content decreased, while it was increased in the presence of 10 mM. The results from intrinsic fluorescence of the protein (excitation at 280 nm) indicated that Ca2+ ion at 1 and 5 mM caused an increase in tertiary structure of the enzyme; however, at 10 mM, a decrease was observed in its tertiary structure. K+ ion at all concentrations increased the tertiary structure of the enzyme. These spectroscopic results are in a good agreement with the thermostability data. It was shown that destabilizing effect of calcium was enthalpic (decrease in ǻH#) whereas the stabilizing effect of potassium was entropic (decrease in ǻS#).
F. Zeinali, A. Homaei,
Volume 9, Issue 1 (1-2018)
Abstract
Aims: Mangroves are subjected to a range of abiotic stresses, which affect their growth and normal physiological processes. One of the most important modes of enzymatic antioxidant defense against stress caused by reactive oxygen species (ROS) is superoxide dismutase (SOD). The aim of this study was to evaluate the antioxidant enzymes activity of superoxide dismutase in the avicennia marina from the Persian Gulf and Gulf of Oman in the presence of the metal ions.
Materials and Methods: In the present experimental study, which was conducted on the leaf of avicennia marina, the sampling was carried out from two habitats including Khamir port in the Persian Gulf and Sirik in the Gulf of Oman and the treatments were carried out in 3 replications. H2O2 sensitivity test and KCN test were used to determine the SOD type. The data were analyzed, using SPSS 19 software by multivariate analysis of variance and Duncan's multiple range test for comparing the means.
Findings: The type of SOD enzyme was detected as Copper-zinc superoxide dismutase (Cu/Zn-SOD). There was no significant difference between different treatments of metals between two regions, and no interaction was observed between metal factor, concentration, and type of region. A strong inhibitory effect was observed in the presence of HgCl2 solution and a weak inhibitory effect was observed in the presence of ZnSo4, FeSo4, and MgCl2 solutions.
Conclusion: Copper, manganese, and cobalt ions significantly increase the activity of the superoxide dismutase, while monovalent ions such as sodium and potassium have little effect on increasing SOD activity and the activity of the antioxidant enzymes of avicennia marina leaf from Khamir port in the Persian Gulf and Sirik in the Gulf of Oman is not different.
Volume 9, Issue 36 (10-2012)
Abstract
Ohmic heating has an advantage over conventional indirect heating methods because heater (electrode) surfaces temperatures are comparatively lower as heat is generated within bulk fluid. Conventional ohmic heating under typical low frequency alternating current (50 or 60 Hz) could cause hydrogen and oxygen evolution due to electrolysis of water. This process could develop the electrodes decay or corrosion. Any decay or corrosion of electrodes shorten the life time and contaminate the food. The main objective of this study was to investigate the rate of the electrodes corrosion in the ohmic heating process. For this purpose the concentrations of Fe, Cr, Ni, Mn, and Mo from the stainless steel electrode migrated into ohmic and conventionally treated soup were measured. In this study migration of the major key metal ions from stainless steel measured by Atomic Absorption. The results showed that overall ohmic treatment yielded the same migration residues of all metal ions, compared to the conventional retorting with similar electrodes. Concentrations of all metal ions migrated into food samples after ohmic treatment were far lower than dietary exposure levels so that this technique can ensure the safety and quality of food supplies.
M. Salehi, M.r. Aghamaali, R. Hasansajedi, S.m. Asghari, Eisa Jorjani,
Volume 10, Issue 1 (3-2019)
Abstract
The fruit of has a lot of acidic proteases and its extract has been used in cheese manufacturing. However, there are few studies about purification and characterization of this enzyme. must be satisfied for the enzyme to be used in industry: 1- stability of enzymes against metal ions and 2- Ability to sustain proper function and stability in the absence of metal ion. Accordingly, in this investigation, the effect of various ions different concentrations activity, stability and somewhat on structural properties of the purified protease were studied. Based on the results, it was shown that the enzyme was relatively stable against NaCl and CaCl2, but by increment of these salts, stability and activity of enzyme . Also, the enzyme was stable against low concentration of various metal ions and only Hg2+ reduces enzyme stability and activity. By studying the role of 2+ of , it was found that 2+ have any role in thermal stability of enzyme at 67˚C. Likewise, by observing the effect of metal ions on of it was that all tested ions increased intensity of emission and caused to shift toward lower wave length. In all, of these showed that the purified enzyme from bad is very stable against various metal heavy metals and it is favorable for industrial application.
F. Shojaei , A. Homaei , M.r. Taherizadeh , E. Kamrani ,
Volume 10, Issue 1 (3-2019)
Abstract
Enzymes of marine organisms are ideal candidates for biomonitoring of pollution in marine environments. For the widespread use of enzymes in industrial processes, carried out under certain physico-chemical conditions, their stability must be improved. In this study, for the first time, chitosan nanoparticles were used as matrices for augmenting the stability of Penaeus vannamei (Whiteleg shrimp)-derived purified proteases against metallic ions. For the electrostatic binding of the enzyme to the chitosan nanoparticles, the protein solution at a concentration of 7mg/ml was added to the nanoparticles, and incubated for 4 hours at 10°C. After 3 times rinsing with phosphate buffer of pH=7.5, the nano-enzyme was dissolved in 1ml phosphate buffer, and used for further studies. The results of this study showed that Fe2+ and Mn2+ significantly increased the enzyme activity, whereas a strong inhibitory effect was observed in the presence of Cd2+, Hg2+, Co2+, Ni2+, Cu2+ and Zn2+, and a weak inhibitory effect in the presence of Na+ and K+. The immobilized enzyme exhibited greater resistance to metal ions than its free counterpart. The free enzyme was susceptible to the presence of metal ions, and with the increment of their concentrations, enzyme activity declines. From this nexus, it could be inferred that the high stability of immobilized enzyme is due to the presence of chitosan nanoparticles. Stability retention of the immobilized enzyme at high concentrations of metal ions indicates the efficacy and utility of the immobilization method in industrial enzyme technology.
