ARS | Publication request: Monitoring of Available Decorin in Different Parts of Bovine Hide during its Processing into Leather

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 30, 2007
Publication Date: December 1, 2007
Citation: Ramos, M., Latona, R.J., Marmer, W.N. 2007. Monitoring of Available Decorin in Different Parts of Bovine Hide during its Processing into Leather. Journal of American Leather Chemists Association. 102(12):404-407.

Interpretive Summary: Among the key components of the collagen framework of skin that undergo changes and removal during conversion of hides into leather is decorin, a proteoglycan (part protein and part carbohydrate). Decorin's persistence may be related to the stiffness of the final leather product. Technology is lacking for accurate and reliable measurement of decorin in hides. An Enzyme Linked Immunosorbent Assay (ELISA) method had previously been developed for determination of decorin core protein in powdered hide samples in this laboratory. The method has now been improved by first dialyzing (a purification step) the extracted hide proteins from intact hides in the presence of collagenase, an enzyme that can break collagen into small fragments. Dialysis removes the high concentration of lime, salts and other potential interfering ingredients such as protein fragments, leaving a cleaner and less viscous solution. The tanning treatment on intact hide, as anticipated, showed a more conservative removal of decorin than observed in powdered hide, giving us a better representation of the actual values. This procedure will assist us in developing a set of standard values of available decorin; changes in the relative tensile strength, stretchability, and softness of a leather product as a result of altered tanning protocols will be correlated to changes in decorin content.

Technical Abstract: During conversion of hides into leather, some hide constituents undergo changes and removal. Among those are decorin, biglycan, sulfated glycosaminoglycan (SGAG) and collagen. Properly monitoring the removal of the predominant and best understood proteoglycan of skin, decorin, was the focus of this work. An ELISA method was improved by dialyzing the guanidine-HCl-extracted proteins in the presence of collagenase, allowing us to obtain a more manageable sample with uniform background and in turn more reliable analytical data. ELISA results on the depletion of decorin in intact hide samples were evaluated and compared among the different parts of bovine hide before and after dialysis. There was a clear difference between undialyzed and dialyzed samples of raw intact hide, whereas after the tanning treatments, the available decorin content was significantly the same from different parts. The amount of decorin that was removed from each area of the hide (shoulder > butt > belly), after processing them using the standard USDA tanning procedure, was directly proportional to the initial amounts. The final available decorin remaining per gram of intact hide in leather (bated samples) was significantly the same in all parts. Based on the dialyzed samples, there was about a 70-78% reduction of available decorin content from raw hide to bated hide samples compared to ~90% in undialyzed samples. The results followed more closely the trend of the SGAG (carbohydrate part of decorin) content determination previously reported by this group, where about a 75% drop was observed from the initial available SGAG content in raw hide to bated hide samples.