Interaction of Divalent Metal Ions with the Hemoglobin of Glossoscolex paulistus: an EPR Study

Abstract

Glossoscolex paulistus is an annelid found in the calcareous region of the state of S. Paulo, Brazil. Its Hb has a M _m of 3,100 kDa (1), and has a subunit structure similar to that of other annelid Hbs. Divalent ions like Ca²⁺ and Mg²⁺ act as effective modulators of O₂ affinity and cooperativity in these giant Hbs (2,3), replacing the phosphates that have this role in tetrameric Hbs. In addition to this functional role, a stabilization of the oligomerie structure has been described as another important effect of divalent ions. It is known that divalent ions prevent the alkaline dissociation of annelid Hbs (4). Despite work in recent years on the role of divalent metal ions in the oxygenation of giant Hbs, very little is known about the binding of these ions to these molecules.