Purification and characterization of metallothionein protein in marine catfish, Arius arius, on exposure to cadmium

• Published in: Biomass conversion and biorefinery 2024-09, Vol.14 (17), p.21095-21105
• Main Authors: Ramalingam, Mani, Govindasamy, Balasubramani, Sumit, Rose, Ayothi, Suresh, Boominathan, Meena
• Format: Article
• Language: English
• Subjects: Biotechnology; Energy; Original Article; Renewable and Green Energy
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-023-04483-4

Fishes are bio-concentrators for heavy metals, but cannot thrive in excessively polluted water. Heavy metals can accumulate in Arius arius , and cadmium (Cd) activates its metal-binding protein. Presently, Cd-binding metallothionein (MT) in A. arius is subjected to sub-lethal cadmium chloride (CdCl 2 at 20 mg/L for 72 h). Separation of MT was achieved from liver homogenate supernatants via affinity chromatography and Sephadex G-25, assessed by 15% SDS-PAGE, verified by Western blotting, and quantified by MALDI-TOF. Using mass fingerprinting, peptide masses were searched in Swiss-Prot. A. arius bounded MT amino acid sequences matched Oreochromis mossambicus with 100%. The 60 amino acids of MT and cysteine content were identified (20 residues). MT contains 6021 daltons based on the MALDI-TOF–MS. The MT protein was modeled using modular9v8 software, confirmed using Ramachandran plot, and utilized as a biomarker for Cd toxicity in fish. The 3D structures might help to identify the binding sites and may lead to innovative treatments for stress and cadmium toxicity.