Sulfur-containing amino acids enhanced antioxidant of yellow mealworm proteins: GPx4 activation through structural modulation evidenced by spectroscopy method

Abstract

Yellow mealworm protein demonstrated antioxidant properties characterized by cumene hydroperoxide radical scavenging activity and weak hydrogen peroxide degradation capacity. Yellow mealworm protein could act as a reducing agentselenium-targeted glutathione peroxidase 4 (GPx4) in the degradation of organic peroxides. Thiol groups were identified through structural characterization using infrared (IR) and Raman spectroscopy: a Raman peak at 2570 cm⁻¹ attributed to the SH bonds of L-cysteine, and that at 705 cm⁻¹ assigned to the vS-C of L-methionine. Total sulfhydryl content was as 0.030 ± 0.003 μmol/mg, and amino acid composition analysis showed that the methionine content was 0.31 ± 0.01 g/100 g. Molecular docking results showed that L-methionine and L-cysteine interact with GPx4 via Se-746. This study proposes that these sulfur-containing amino acids act as functional analogs of selenocysteine and can bind to the catalytic site of GPx4 to enhance its enzymatic antioxidant activity. This mechanism may be the reason why yellow powdery worm proteins are resistant to oxidation.