title: Critical role of zinc in hardening of Nereis jaws.
abstract: Hardening of invertebrate jaws and mandibles has been previously correlated to diverse, potentially complex modifications. Here we demonstrate directly, for the first time, that Zn plays a critical role in the mechanical properties of histidine-rich Nereis jaws. Using nanoindentation, we show that removal of Zn by chelation decreases both hardness and modulus by over 65%. Moreover, reconstitution of Zn yields a substantial recovery of initial properties. Modulus and hardness of Zn-replete jaws exceed those attainable by current engineering polymers by a factor of >3. Zn-mediated histidine cross-links are proposed to account for this enhancement in mechanical properties.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California at Santa Barbara, Santa Barbara, CA 93106, USA. Broomell@lifesci.ucsb.edu
authors.forename: Chris C
authors.initials: CC
authors.lastname: Broomell
authors.forename: Mike A
authors.initials: MA
authors.lastname: Mattoni
authors.forename: Frank W
authors.initials: FW
authors.lastname: Zok
authors.forename: J Herbert
authors.initials: JH
authors.lastname: Waite
mesh_terms: D000818:Animals; D006639:Histidine / Q000737:chemistry / Q000378:metabolism; D007568:Jaw / Q000033:anatomy & histology / Q000737:chemistry / Q000378:metabolism; D011077:Polychaeta / Q000033:anatomy & histology / Q000737:chemistry* / Q000378:metabolism; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism
chemical_list: D006639:Histidine; D015032:Zinc