Background Aim of the study was to immobilize the α-amylase produced earlier from the mesophilic fungus Rhizoctonia solani AG-4 strain ZB-34 by solid-state fermentation and investigate the suitability of immobilized enzymes for some industries. Materials and methods A novel α-amylase from R. solani AG-4 strain ZB-34 was immobilized in chitosan by covalent binding and Ca-alginate by entrapment. Results The efficiency of chitosan and Ca-alginate immobilization was 67.9% and 59.6%, respectively. The immobilized enzymes showed the highest activity in the presence of starch. Optimum values for chitosan and Ca-alginate immobilized enzymes were pH 4.50 and 40°C and pH 5.50 and 60°C, respectively. It was found that immobilized enzymes were highly stable in terms of thermal and pH stabilities. When the chitosan immobilized enzyme was used with detergents, chocolate stains on dirty laundry was better cleaned. Chitosan immobilized R. solani AG-4 strain ZB-34 α-amylase was found to have a higher desizing effect at 40°C in tap water. As a result of Ca-alginate immobilization, the enzyme clarified apple juice more than the free enzyme. Conclusion The results showed that immobilized enzymes might have potential applications in industry. This is the first report immobilizing an α-amylase produced from the fungus R. solani.
An esterase from Lycoperdon pyriforme was characterized. The enzyme had a maximum activity at pH 8.0 and 40C with p‐nitrophenyl acetate as a substrate. Km and Vmax values were calculated as 2.13 mM and 0.65 U/mg protein, respectively. The enzyme activity was conserved more than 90% over a broad range of pH (3.0–9.0) at 4C after 24 h of incubation. The activity increased 37 ± 3.6% after 120 min of incubation at 40C. Li+, Mg2+ and Ca2+ activated the enzyme 12 ± 1.8, 16 ± 2.5 and 15 ± 2.5%, respectively. The esterase was inhibited in different ratios by some detergents such as Triton X‐114, Triton X‐100, Tween 20 (Sigma Chemical Co., St. Louis, MO) and sodium dodecylsulfate. It retained most of its activity in the presence of methanol and dimethylsulphoxide at the final concentration of 10% (v/v). pH and moderate thermal stability of L. pyriforme esterase and its activity in some organic solvents could make it useful for some industrial purposes such as detergent and paper industry. PRACTICAL APPLICATIONS Esterases play a major role in the degradation of natural materials and industrial pollutants, viz., cereal wastes, plastics and other toxic chemicals. They are also useful in the synthesis of optically pure compounds, perfumes and antioxidants. Because of these biocatalytic applications, it may be interesting to study novel esterases from different organisms. Therefore, it is important to study esterase activity of Lycoperdon pyriforme. In this way, a new esterase having potential applications can be found.
Background Tyrosinase plays a central role in the biosynthesis pathway of melanin pigment. Melanin protects human skin against radiation and its unusual levels cause some skin disorders such as pregnancy scar, oldness spots and melanoma. Tyrosinase has also been linked to Parkinson’s and other neurodegenerative diseases. In addition, melanin plays a critical role as a defense molecule for insects during wound healing and is important for their life. Therefore, determination of inhibitor molecules for tyrosinase has a promising potential for therapies of some diseases and is an alternative method for keeping insects under control. Material and methods In this study, 1-hepthyl-3-(4-methoxybenzyl)-4H-1,2,4-triazole-5-one derivative (A6, A8, A15) and 3-(4-chlorophenyl)- 5-(4-methoxybenzyl)-4H-1,2,4-triazole (B5, B9, B13) derivative compounds were evaluated in terms of their potential for mushroom tyrosinase inhibition. IC50 values of these six molecules were determined. Results It was seen that B9 molecule was the most effective inhibitor. Docking studies also nearly supported this end result. Tyrosinase inhibition type and Ki value were found to be uncompetitive and 370.7±0.3 μM, respectively, in the presence of B9 compound. Conclusion These results suggest that B9 compound is a potential tyrosinase inhibitor.
In this work, Geobacillus sp. TF16 phytase was separately immobilized in chitosan and Ca-alginate with the efficiency of 38% and 42%, respectively. These enzymes exhibited broad substrate specificity. Maximal relative phytase activity was measured at pH 5.0 and 95°C and pH 3.0 and 75°C for chitosan and Ca-alginate, respectively. The enzymes were highly stable in a wide pH and temperature range. Values of K m and V max were determined as 2.38 mM and 3401.36 U/mg protein for chitosan, and 7.5 mM and 5011.12 U/mg protein for Ca-alginate. The immobilized enzymes showed higher resistance to proteolysis. After 4 h incubation, hydrolysis capacities of chitosan-and Ca-alginate immobilized enzymes for soymilk phytate were calculated as 24% and 33%, respectively. The chitosan-and Ca-alginate immobilized phytases conserved its original activity after 8 and 6 cycles of reuse, respectively. The features of the enzymes were very attractive and they might be useful for some industrial applications.
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