Multiple conformations at functional site of hemerythrin: Evidence from resonance Raman spectra.

Area of Science:

• Biochemistry
• Spectroscopy
• Protein Chemistry

Background:

• Hemerythrin is an oxygen-binding protein.
• Understanding its functional site is crucial for biochemistry.

Purpose of the Study:

• To investigate the vibrational properties of hemerythrin and its ligand complexes.
• To explore the conformational states of the hemerythrin functional site.

Main Methods:

• Resonance Raman spectroscopy was used.
• Monomeric and metmyohemerythrin adducts were analyzed.
• Isotope exchange studies in H(2)(18)O were performed.

Main Results:

• Ligand vibrations and Fe-O frequencies are independent of protein quaternary structure.
• Anionic adducts exhibit distinct isotope exchange behaviors.
• A photochemical transformation between exchange behaviors was observed.

Conclusions:

• The hemerythrin functional site exists in at least two conformational states.
• Irradiation can induce isotope exchange in the exchange-resistant form.
• These findings advance our understanding of hemerythrin's structure-function relationship.