ARS | Publication request: APPROACH TO A TANNING MECHANISM: STUDY OF THE INTERACTION OF ALUMINUM SULFATE WITH COLLAGEN

Submitted to: American Leather Chemists Association Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2004
Publication Date: June 1, 2004
Citation: Brown, E.M., Dudley, R.L. 2004. Approach to a tanning mechanism: study of the interaction of aluminum sulfate with collagen [abstract]. American Leather Chemists Association Meeting. Paper No. 29.

Technical Abstract: The production of leather from animal hides or skins is accomplished through the use of tanning agents that stabilize the collagen matrix. The molecular characteristics of tanning agents are quite varied, and led to the expectation that leathers produced with different tanning agents would have fundamentally different structures. Current proposals suggest that the structural similarities between leathers produced with different tanning agents are likely to be greater than the differences. The goal of this work is to contribute to the elucidation of a general mechanism for tanning. Although complex salts of Cr(III) are currently the most effective tanning agents, salts of other metals, including aluminum, have been used either alone or in combination with vegetable tannins or other organic chemicals. In the present study, the interaction of aluminum sulfate with collagen is investigated. In a model system, using soluble collagen, 13C NMR spectroscopy showed that Al(III) formed a complex with carboxyl groups on collagen. 27Al NMR revealed the formation of a second sphere complex between collagen and aluminum. The effects of Al(III) binding on the thermal stability of collagen were studied by circular dichroism spectroscopy of soluble complexes and differential scanning calorimetry of insoluble complexes. Comparison of Al(III)-collagen interactions with Cr(III)-collagen interactions is expected to provide insight into a more generalized mechanism for tanning.