XAFS Studies of Transition Metal and Halogen Biomaterials in Invertebrate Tools

A significant fraction of arthropods, as well as some worms and members of other phyla, contain extraordinary amounts of transition metals (Mn, Fe, Cu, Zn) and halogens (Cl, Br, I) in their hardened tools (jaws, claws, fangs, stings, etc.). Bulk Zn EXAFS differs for different kinds of tools, whereas Br appears to occupy a common environment in different tools. Zn binding to histidine is observed for most samples but bulk Zn EXAFS is likely to sample a mixture of Zn coordination environments. Principal Component Analysis (PCA) suggests the presence of three main Zn coordination components. The similar Br EXAFS in widely different tools indicates that Br‐phenyl is the dominant form, suggesting the presence of brominated aromatic amino acid‐derived organic components in these biomaterials. Calculated Debye‐Waller factors are used to simulate EXAFS when model compound data are unavailable.