Manganese and “pinnaglobin” in Pinna nobilis☆

Abstract The hemolymph and extrapallial fluid of the Mediterranean mollusc Pinna nobilis have been shown to contain Mn(II) at concentrations in excess of five orders of magnitude over those normally found in seawater. In the case of the extrapallial fluid, the Mn(II) is associated exclusively with a manganese-binding polypeptide of molecular weight ca . 2,200 daltons. This is in direct contrast to the findings of some other authors, e.g. Ghiretti et al. (8), who report the absence of detectable manganese in both the hemolymph and extrapallial fluid of the same organism. Also, in contrast to another earlier claim by Griffiths (9), the mangano-peptide (previously called “pinnaglobin” by Griffiths) does not reversibly bind molecular oxygen. Therefore, in order to avoid the misleading use of the term “globin” with reference to this molecule, the alternate name “manganochelitin” is suggested.