The tyrosinase of Penicillium chrysogenum strain AUMC 14100 Accession No. MN219732 was purified to homogeneity and chemically modified by N-ethylmaleimide (NEM) and 5-(dimethylamino)naphthalene-1-sulfonyl chloride (dansyl chloride, DC). The inactivation of the purified enzyme obeyed pseudo-first-order reaction kinetics in the presence of NEM and DC (1-5 mM).The rate constants of the enzyme inactivation by NEM and DC were calculated to be 0.083 mol/min and 0.0013 mol/min, respectively. The recovery of enzyme activity by the protective effect of substrate indicates a non-specific modification of the active center. The order of tyrosinase inactivation kinetics and the substrate protection revealed the essentiality of sulfhydryl and lysyl residues in the enzyme active site and its role in the enzyme catalysis. The immobilized tyrosinase on alginate showed a gradual increase in residual activity over the immobilization time until the fourth hour. The desorptivity of tyrosinase was gradually raised with higher sodium dodecyl sulfate (SDS) concentrations. The immobilized enzyme retained about 70% of its original activity after 8 repeated cycles. Thus, immobilized tyrosinase of Penicillium chrysogenum removed 75% of phenol after 8 cycles and thus seems likely to be a good candidate for phenol removal in aqueous solution.

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Environmental pollution due to the continuous uncontrolled discharge of toxic dyes into the water bodies provides insight into the need to eliminate pollutants prior to discharge is significantly needed. Recently, the combination of conventional chemotherapeutic agents and nanoparticles has attracted considerable attention. Herein, the magnetic nanoparticles (Fe3O4-NPs) were synthesized using metabolites of Aspergillus niger. Further, the surfaces of Fe3O4-NPs were functionalized using 3-mercaptoproionic acid as confirmed by XRD, TEM, and SEM analyses. A purified P. expansum laccase was immobilized onto Fe3O4/3-MPA-SH and then the developed immobilized laccase (Fe3O4/3-MPA-S-S-laccase) was applied to achieve redox-mediated degradation of different dyes. The Fe3O4/3-MPA-S-S-laccase exhibited notably improved stability toward pH, temperature, organic solvents, and storage periods. The Fe3O4/3-MPA-S-S-laccase exhibited appropriate operational stability while retaining 84.34% of its initial activity after 10 cycles. The catalytic affinity (Kcat/Km) of the immobilized biocatalyst was increased above 10-fold. The experimental data showed remarkable improvement in the dyes’ decolorization using the immobilized biocatalyst in the presence of a redox mediator in seven successive cycles. Thus, the prepared novel nanocomposite-laccase can be applied as an alternative promising strategy for bioremediation of textile wastewater. The cytotoxic level of carboplatin and Fe3O4-NPs singly or in combination on various cell lines was concentration-dependent.

The aim of this work was to determine the maximum catalytic activity and intracellular location of NADP(+)-linked malic enzyme (EC 1.1.1.40) in C3 plants. Appreciable activities, ranging from 80 to 712 nmol · (gFW)(-1) · min(-1), were found in a wide range of tissues (roots and leaves of Pisum sativum L., cotyledons of Cucurbit a pepo Alef., developing seeds of Brassica napus L., mesocarp of Persea americana Gaertn., and suspension cultures of Glycine max L.). Overall, activity showed a rough positive correlation with biosynthesis. Differential and density-gradient fractionation of extracts of the cotyledons of germinating marrow (C. pepo) and lysates of protoplasts of suspension cultures of G. showed that the enzyme had the same distribution as the plastid marker enzymes. It is suggested that in C3 plants NADP(+)-linked malic enzyme is confined to the plastids and involved in biosynthesis.

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Abstractβ-Glucanase has received great attention in recent years regarding their potential biotechnological applications and antifungal activities. Herein, the specific objectives of the present study were to purify, characterize and immobilize β-glucanase from Aspergillus niger using covalent binding and cross linking techniques. The evaluation of β-glucanase in hydrolysis of different lignocellulosic wastes with subsequent bioethanol production and its capability in biocontrol of pathogenic fungi was investigated. Upon nutritional bioprocessing, β-glucanase production from A. niger EG-RE (MW390925.1) preferred ammonium nitrate and CMC as the best nitrogen and carbon sources, respectively. The soluble enzyme was purified by (NH4)2SO4, DEAE-Cellulose and Sephadex G200 with 10.33-fold and specific activity of 379.1 U/mg protein. Tyrosyl, sulfhydryl, tryptophanyl and arginyl were essential residues for enzyme catalysis. The purified β-glucanase was immobilized on carrageenan and chitosan with appreciable yield. However, the cross-linked enzyme exhibited superior activity along with remarkable improved thermostability and operational stability. Remarkably, the application of the above biocatalyst proved to be a promising candidate in liberating the associate lignocellulosic reducing sugars, which was utilized for ethanol production by Saccharomyces cerevisiae. The purified β-glucanase revealed an inhibitory effect on the growth of two tested phytopathogens Fusarium oxysporum and Penicillium digitatum.

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