Introducing a Thermo-Alkali-Stable, Metallic Ion-Tolerant Laccase Purified From White Rot Fungus Trametes hirsuta

Abstract

This study introduces a valuable laccase, designated ThLacc-S, purified from white rot fungus Trametes hirsuta. ThLacc-S is a monomeric protein in nature with a molecular weight of 57.0 kDa and can efficiently metabolize endocrine disrupting chemicals. The enzyme was successfully purified to homogeneity via three consecutive steps consisting of salt precipitation and column chromatography, resulting in a 20.76-fold increase in purity and 46.79% yield, with specific activity of 22.111 U/mg protein. ThLacc-S was deciphered as a novel member of the laccase family and is a rare metalloenzyme that contains cysteine, serine, histidine, and tyrosine residues in its catalytic site, and follows Michaelis-Menten kinetic behavior with a Km and a kcat/Km of 87.466 μM and 1.479 s–1μM–1, respectively. ThLacc-S exerted excellent thermo-alkali stability, since it was markedly active after a 2-h incubation at temperatures ranging from 20 to 70°C and retained more than 50% of its activity after incubation for 72 h in a broad pH range of 5.0–10.0. Enzymatic activities of ThLacc-S were enhanced and preserved when exposed to metallic ions, surfactants, and organic solvents, rendering this novel enzyme of interest as a green catalyst for versatile biotechnological and industrial applications that require these singularities of laccases, particularly biodegradation and bioremediation of environmental pollutants.

Insights into the Applications of Extracellular Laccase-Aided Humification in Livestock Manure Composting

“…T2 Cu is colorless, and T3 Cu consists of a pair of Cu atoms that give a weak absorbance. 50,54 T2 and T3 Cu atoms form a trinuclear copper cluster (TNC) where the binding and multielectron reduction of dioxygen takes place. 55,56 2.2.…”

“…63 Moreover, enzymatic humified functions can be impeded by inorganic minerals, chelators, detergents, and other compounds, or laccase may be inactivated by binding to particles or organic matter. 54 Application of free enzyme is, therefore, not practicable, in particular, not in large-scale purification processes and under successive conditions. 64 Enzymatic immobilization overcomes some of the aforementioned drawbacks by improving some of laccase properties.…”

“…T1 Cu is responsible for the intense blue color of laccase due to the forceful electronic absorption of the Cu–Cu linkages. T2 Cu is colorless, and T3 Cu consists of a pair of Cu atoms that give a weak absorbance. , T2 and T3 Cu atoms form a trinuclear copper cluster (TNC) where the binding and multielectron reduction of dioxygen takes place. , …”

“…The utilization of free laccase for the quality improvement of end products in LM composting is probably limited, owning to its low stability and high production costs . Moreover, enzymatic humified functions can be impeded by inorganic minerals, chelators, detergents, and other compounds, or laccase may be inactivated by binding to particles or organic matter . Application of free enzyme is, therefore, not practicable, in particular, not in large-scale purification processes and under successive conditions .…”

Improvement of Laccase Production by Thielavia terrestris Co3Bag1. Enhancing the Bio-Catalytic Performance of the Native Thermophilic TtLacA via Immobilization in Copper Alginate Gel Beads

“…[ 73 ], which shows an increase in the relative activity in the presence of Cu 2+ . Similarly, an increase in the enzymatic activity of laccases ThLacc-S from T. hirsuta [ 74 ] and Tplac from Trametes pubescens [ 72 ] was enhanced with the ion Cu 2+ at 25 mM. Free Tt LacA was strongly inhibited by Fe 2+ and Hg 2+ .…”