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ARS Home » Research » Publications at this Location » Publication #193551
Title: PROTEIN-TRANSITION METAL ION NETWORKS

Author
item Barone, Justin
item Dangaran, Kirsten
item CHIN, SYLVIA - USDA-ARS

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/26/2006
Publication Date: 6/26/2006
Citation: Barone, J.R., Dangaran, K.L., Chin, S. 2006. Protein-transition metal ion networks [abstract]. American Chemical Society Abstracts. Toxics and Materials Paper 80.

Interpretive Summary: In biology, it is known that transition metal ions bind to proteins. In this work, metals are bound to agricultural proteins to show that they can "cross-link" the protein and increase certain properties like stiffness and water permeability resistance. This is important since many agricultural proteins suffer from a lack of stiffness and permeability resistance in their native state. The study shows that it is easy to overcome these difficulties and will aid in the commercialization of products made from agricultural proteins.

Technical Abstract: Proteins obtained from agricultural sources were blended with divalent metal ions. Feather keratin, egg albumin, and wheat gluten had low, medium, and high levels of aspartic and glutamic acid, respectively, and FT-IR showed that the divalent transition metal ions Mn2+, Cu2+, and Zn2+ were tightly bound to the proteins at least at the secondary acid sites. Birefringence experiments performed concurrently with tensile experiments showed refractive index changes indicative of network formation. This resulted in a 3-4 times increase in stiffness. Increasing concentrations of ions resulted in increased stiffness. Binding divalent alkaline earth metal Ca2+ ions did not result in the same increase. Addition of Zn2+ to egg albumin resulted in a 34% decrease in water permeability but no change in oxygen permeability. Preliminary electrical conductivity experiments show a clear split between the conductivities of materials blended with different metal ions, with copper-wheat gluten having the highest electrical conductivity.