Critical role of zinc in hardening of Nereis jaws.
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.
Broomell
Chris C
CC
Department of Molecular, Cellular, and Developmental Biology, University of California at Santa Barbara, Santa Barbara, CA 93106, USA. Broomell@lifesci.ucsb.edu
Mattoni
Mike A
MA
Zok
Frank W
FW
Waite
J Herbert
JH
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
D006639:Histidine; D015032:Zinc