Distribution and Role of Trace
Transition Metals in Glycera Worm Jaws Studied with Synchrotron Microbeam
Lichtenegger HC, Birkedal H, Casa DM, Cross JO, Heald SM, Waite JH, Stucky GD
CHEMISTRY OF MATERIALS: 17 (11), April, 2927-2931 (2005)
A combination of position-resolved synchrotron microbeam techniques was used
to explore the
distribution and role of trace transition metals in the jaws of Glycera dibranchiata.
The mandibles of
this marine sediment worm have recently been found to be reinforced by the
atacamite [Cu2(OH)3Cl]. Here we show that the system is more complex, containing
zinc and iron and
unmineralized copper compounds as well. X-ray absorption spectroscopy studies showed that a fraction
of copper is present in oxidation state, Cu(I), in contrast to the mineral
that exclusively contains Cu(II).
X-ray fluorescence imaging revealed traces of copper also in the jaw base devoid
of mineral. Traces of
iron were found as well, but occurred spatially correlated with the copper
mineral, suggesting a substitution
of copper atoms by iron in the atacamite mineral. Zinc was evenly dispersed
throughout the jaw matrix,
quite in analogy to zinc in Nereis jaw, a related worm species, where nonmineralized
zinc serves to
cross-link and harden the proteinaceous matrix.