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l-Asparaginase
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2020
It is reported that enzyme activity is either enhanced or inhibited in the presence of certain elements. The element that has a positive influence on enzyme activity is termed as the enzyme activator and the element that inhibits or suppresses the enzyme activity is called the enzyme inhibitor. Generally, metal ions are examined for their effect on enzyme activity. Many metal ions act as enzyme co-factor and in their presence enzyme activity increases. There are many studies carried out to examine the effect of such elements on l-asparaginase activity where the enzyme is isolated from different sources. Raha et al. (1990) isolated this enzyme from a mesophilic fungus namely Cylindrocarpon obtusisporum MB-10. The optimum pH and temperature observed for the enzyme are 7.4 and 37°C, respectively. The pI was found to be 5.5. The isolated enzyme was identified as a tetramer composed of four identical subunits and was conjugated with 37.3% (w/w) carbohydrate. It was found that metal ions like Zn2+, Fe2+, Cu2+, Hg2+, and Ni2+ has negative impact on enzyme activity. When metal chelators like EDTA, CN–, and cysteine were examined for their effect on enzyme activity, they are found to be enzyme activators in this case. This suggests that the isolated enzyme is not a metalloprotein. At the same time, the enzyme activity is also increased by reduced glutathione presence and decreased in the presence of dithiothreitol and 2-mercaptoethanol (Raha et al., 1990). Tsavdaridis et al. (1994) isolated and purified two subtypes of this enzyme from Tetrahymena thermophila. The optimum pH determined for the enzyme was 8.6, whereas isoelectric point determined for type I and type II were 7.4 and 8.6, respectively. The both subtypes showed elevated enzyme activity in the presence of different ions and showed maximum enzyme activity in the presence of Ca2+ (Tsavdaridis et al., 1994). Similarly, co-occurrence of the two sub-types is reported in Arabidopsis where the enzyme activity is reported to be influenced by K+. Even the recombinant form of this enzyme At3g16150 showed 10-fold increase in catalytic activity (Bruneau et al., 2006). Various other elements such as Cu2+, diphosphate, EDTA, I–, Li+, Mg2+ have been reported to have direct or indirect role in the catalytic activity of this enzyme isolated from different sources.
Potential of plant mediated biosynthesis of iron nanoparticles and their application in dye degradation process
Published in Journal of the Air & Waste Management Association, 2023
Reena Jain, Guncha Sharma, Shailender Kumar, Anita Dubey, Nikita Gakhar, Chirashree Ghosh
Atomic absorption spectroscopy was done for all the degraded leftover dye samples to detect the leaching of iron, if any, from the nanoparticles. To analyze samples for the same, all 60 samples were taken as shown in Figure 12. It is reported that at low concentrations, iron plays an important role in metabolic and fermentation processes, as an enzyme activator, stabilizer, and functional component of proteins. Above trace levels, however, iron has other roles. It has been stated that iron, has fairly narrow “concentration window” between the essential and toxic levels. Iron is a moderately toxic element when compared with other transition metals. However, the toxic doses of iron and its compounds can lead to serious problems, including depression, rapid and shallow respiration, coma, convulsions, and cardiac arrest. Thus, appropriate knowledge of the iron content is highly desirable. So, the toxicity of this element demands a fast and accurate method for its determination in water (Steponeniene, Tautkus, and Kazlauskas 2003).