Substrate specificity of a new laccase from Trametes polyzona WRF03

Abstract

Various aromatic compounds that are structurally analogous to lignin were tested as possible/preferred substrates for purified laccase from newly isolated white rote fungi, Trametes polyzona WRF03. The pH optima were tested using different substrates and kinetic studies were conducted at these pH optima. The pH optima in the presence of ABTS, α-naphthol, o-dianisidine, and catechol were 4.5 but 5.0 and 5.5 in the presence of guaiacol and pyrogallol, respectively. The initial velocities obtained from the kinetic study were analyzed using Graph Pad Prism 7 and Lineweaver-Burk plot to obtain kinetic constants ( k m and Vmax ) which were used to calculate substrate specificity. Amongst all the substrates tested, ABTS had the highest specificity-constant (181.51 M −1 s −1 ), and therefore, the most preferred substrate was followed by α-naphthol, o -dianisidine, guaiacol, pyrogallol, and catechol. Resorcinol, orcinol, and veratryl alcohol did not display any considerable chemical shift in the presence of Trametes polyzona WRF03 laccase. Also, oxidation of phenolic substrates appeared to be dependent on the nature of the substituent groups and their relative position on the aromatic nucleus. Since most of these substrates are structural analogs of lignin and many recalcitrant environmental pollutants, the enzyme may find application in delignification, treatment of wastewater containing dyes, and polycyclic aromatic hydrocarbons (PAHs).

Purification and biochemical characterization of two laccase isoenzymes isolated from Trichoderma harzianum S7113 and its application for bisphenol A degradation

“…Laccases have the ability to delignify, decolorize, and detoxify dyes from effluents, remove stains from biomaterials, and remediate polluted environments because they have the potential to catalyze towards aromatic substrates (mostly phenols) [ 7 , 57 ].Substrate specificity for both isoenzymes was determined against some laccase-specific substrates (Table 4 ). ABTS with a concentration of 0.3 mM showed the highest relative activity for both Lac A and Lac B and was the most suitable substrate for the two isoenzymes under study.…”

“…Laccase from Magnaporthe grisea had the ability to oxidize the tested substrates in the order of: syringaldazine, L-3,4-dihydroxyphenylalanine (DOPA), ferulic acid, α-naphthol, hydroquinone, guaiacol, p-cresol, catechol, and 4-methylcatechol [ 58 ]. Moreover, laccase from Trametes polyzona WRF03 had the ability to oxidize these ordered substrates: ABTS, α-naphthol, o-dianisidine, pyrogallol, guaiacol, catechol, resorcinol, orcinol, and veratryl alcohol [ 7 ].…”

“…Numerous environmental pollutants, such as bisphenol A (BPA), may be successfully broken down and mineralized by fungi using their laccases [ 20 , 21 ]. Laccase belongs to the polyphenol oxidases family, and its active site contains four copper atoms from types T 1 , T 2 , and T 3 [ 6 , 7 ]. The type-1 copper center is in charge of the substrate's initial oxidation, whereas the type-2 and type-3 copper types combine to form a trinuclear center, which is where the laccase catalytic activity occurs [ 4 , 8 , 9 ].…”

Design and Optimization of Laccase Immobilization in Cellulose Acetate Microfiltration Membrane for Micropollutant Remediation

“…Compared to the substrate used for optimization, the rate and the mechanism of DCF removal is different, since the transformation of ABTS has the highest reaction rate among other substrates [62]. The degradation of DCF was performed in buffering solutions, so the changes in pH were eliminated.…”

Electrochemistry of copper efflux oxidase-like multicopper oxidases involved in copper homeostasis

“…Last but not least, in McoA, the loop close to the CuT1 was demonstrated by molecular dynamics simulation and X-ray scattering to control substrate access [30]. As an almost general rule, restricted organic substrate accessibility leads to a 1-2 orders higher Michaelis constant (Km) for organic substrates such as 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) than in classical MCOs [15,26,[36][37][38][39][40]. Accordingly, E. coli CueO mutant lacking the Met-rich region was capable of efficiently oxidizing ABTS [40].…”