Abstract
This study investigates the essential role of the heme cavity in the peroxidase and antibacterial activities of homodimeric hemoglobin (Tg-HbI) from the blood clam Tegillarca granosa. After treatment with sodium dodecyl sulfate (SDS), the peroxidase and antibacterial activities of the Tg-HbI were significantly inhibited, with the degree of inhibition correlating positively with the SDS concentration. Fluorescence spectroscopy, UV-Vis spectroscopy, and molecular docking analysis further revealed that SDS interacts with key amino acid residues (e.g., His70 and His102) in the heme cavity of Tg-HbI, causing conformational changes that disrupt the internal hydrophobic interactions, thus inhibiting its function. This study confirms that the antibacterial effect of Tg-HbI is mediated through its peroxidase activity and that the heme cavity plays a critical role in maintaining this activity. These findings lay a foundation for further research on the immune defense functions of hemoglobin and provide new insights into the mechanisms of environmental adaptation in T. granosa.