Laccase-Catalyzed Oxidation of Thyroid Hormones

Laccase (oxygen oxidoreductase, EC 1.10.3.2, from Trametes versicolor, ≥0.5 U mg⁻¹), 3,3′,5-triiodo-l-thyronine ≥95% (fT3), antibody protein disulfide isomerase family A, member 3 (PDIA3) (Anti-PDIA3) produced in rabbit 0.10 mg mL⁻¹ (Ab), ascorbic acid (AA), tyrosine (Tyr), Human Serum from human female AB plasma, USA origin, sterile-filtered, bovine serum albumin (BSA), and Fe₃O₄@graphene nanocomposite, 10 mg mL⁻¹ dispersion in acetone (Product of USA), were purchased from Sigma-Aldrich Co (Merck company). Citric acid (CA), NaOH, NaH₂PO₄, Na₂HPO_4, KH₂PO₄, Tris, HCl, CH₃COONa, CH₃COOH, NaCl, KCl, and glutaraldehyde (GA) were purchased from POCH (Part of Avantor, Performance Materials, Poland). Levothyroxine (Euthyrox N 75) was manufactured by Merck. All chemicals were of analytical grade and were used without further purification. All buffers were prepared according to generally known, obligatory standards.