Meeting Abstract

4.1  Tuesday, Jan. 4  Cross-linking by protein oxidation in gastropod glues SMITH, A.M.*; BRADSHAW, A.; SALT, M.; BELL, A.; LITRA, N.; Ithaca College, NY; Ithaca College, NY; Ithaca College, NY; Ithaca College, NY; Ithaca College, NY asmith@ithaca.edu

Protein oxidation is a common phenomenon that causes protein dysfunction in aging, but it can also be harnessed to strengthen biomaterials. Collagen and elastin in animal connective tissues are cross-linked by a metal-catalyzed oxidation system that leads to the formation of bonds between oxidized amino acids and nucleophilic amino acid side chains. Here we show that the glue produced by the terrestrial slug Arion subfuscus may use a similar mechanism but with different proteins. Immunoblotting for carbonyl groups demonstrated that several key proteins in the glue are heavily oxidized, and this oxidation appears to occur rapidly. The carbonyl groups were not easily detected unless the glue was denatured, though, suggesting that they may be unavailable due to participation in reversible cross-links. This was tested using reagents that normally modify carbonyls. The strong reducing agent sodium borohydride and the nucleophile hydroxylamine should eliminate any accessible carbonyl groups. In the glue however, borohydride had no effect on carbonyl content while hydroxylamine partially modified the carbonyls; this was consistent with the way each reagent would interact with cross-links between carbonyls and primary amines. The two treatments also impacted protein solubility in a way that was consistent with this proposed cross-linking mechanism. Thus, slugs may harness protein oxidation to strengthen their glue. Because the components involved in protein oxidation are common, it is likely that this could represent a relatively widespread but underappreciated mechanism for strengthening biomaterials.