Purification and characterization of a novel alkaline laccase produced by Acinetobacter sp. M6

A novel bacterial laccase enzyme was isolated and purified from Acinetobacter sp. strain M6 was purified by ammonium sulfate precipitation followed by ion-exchange and gel filtration chromatography which resulted in 17.5-fold higher specific activity compared to the raw extract. The molecular weight was approximated as 62 kDa by using SDS-PAGE. It was observed that the enzyme showed its optimal performance level and sustained its stability against heavy metals, organic solvents and halide ions at pH 7.2 and 40 °C. The most suitable substrates for the enzyme were found to be ABTS and DMP as the end-point measurements were locate. It was demonstrated that the enzyme showed notable bioconversion capabilities for absorbing heavy metals such as Cd²⁺ along with Pb²⁺ where it showed absorption rates of 89% and 75% respectively while achieving dye decolorization at 85% for malachite green and 72% for reactive black 5. Enzymatic kinetic values found to be 0.092 mM Km together with 196 U/mg Vmax for ABTS. Test results established an The isoelectric point (pI) was determined as 6.34 by isoelectric focusing which matches observations from standard bacterial laccases. By LC-MS/MS analysis, it was found that the protein chain consisted of 489 amino acids. The protein sequence demonstrated high similarity to other multicopper oxidase family laccases by preserving the copper-binding patterns HXHG, HXH, and HXXHXH. The production of a novel laccase from Acinetobacter sp. M6 has been confirmed through research which demonstrates its industrial prospects especially during environmental remediation involving dye decolorization and heavy metal bioremediation.