The effects of biliverdin on pressure-induced unfolding of apomyoglobin: The specific role of Zn2+ ions
Résumé
Apomyoglobin (apoMb), a model protein in biochemistry, exhibits a strong propensity to bind various ligands, which makes it a good candidate as a carrier of bioactive hydrophobic drugs. The stability of its hydrophobic pocket determines its potential as a carrier of bioactive compounds. High pressure (HP) is a potent tool for studying protein stability, revealing the specific role of hydrophobic cavities in unfolding. We probed the effects of biliverdin (BV) binding and its complex with Zn 2+ ions on the structure and HP stability of apoMb. CD spectroscopy and SAXS measurements revealed that BV and BV-Zn 2+ complexes make the apoMb structure more compact with higher α-helical content. We performed in-situ HP measurements of apoMb intrinsic fluorescence to demonstrate the ability of BV to stabilise apoMb structure at HP conditions. Furthermore, the presence of Zn 2+ within the apoMb-BV complex significantly enhances the BV stabilisation effect. In-situ visible absorption study of BV chromophore confirmed the ability of Zn 2+ to increase the stability of apoMb-BV complex under HP: the onset of complex dissociation is shifted by ~100 MPa in the presence of Zn 2+. By combining HPfluorescence and HP-visible absorption spectroscopy, our strategy highlights the crucial role of tetrapyrrole-metal complexes in stabilising apoMb hydrophobic pocket.
Domaines
Biologie structurale [q-bio.BM]
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