PROPERTIES OF BOVINE HAIR KERATINS SOLUBILIZED WITH THIOGLYCOLATE

Partially decomposed hair, created during conventional hide processing in the beamhouse, is one of the strongest pollutants in the tannery e ffluent. One of the approaches that has been taken to reducing the pol lution from the unhairing process is to remove intact hair from the hi des by using conventional reagents in novel ways that loosen rather th an digest the hair. This paper considers the reductive solubilization of recovered hair from raw hide with the final goal being to utilize i t as a bio-material. In the present study, three kinds of solubilizing solutions were tested: 0.1 M thioglycolate at pH 11,35 degrees C(TG-1 1), 0.1 M thioglycolate containing 6M guanidine at pH 7, 35 degrees C (TG/G-7), and 0.1 M thioglycolate containing 6 M urea at DH 7, 35 degr ees C (TG/U-7). About 60% of the original hair weight was recovered as the product became solubilized with TG-11. The recovered protein had good solubility in solvent buffer without reducing agent. Approximatel y the same extent of solubilization was attained with TG/G-7 at neutra l pH. The resultant preparation was almost insoluble unless the solven t contained the reducing agent. On the other hand, the extent of solub ilization with TG/U-7 was significantly low. In SDS-PAGE, sodium dodec yl sulfate-polyacrylamide gel electrophoresis, major bands of 45kD and 55kD reported as elemental fragments of microfibrilar protein of wool were commonly observed in the products solubilized with TO-Il and TG/ G-7. Thus the solubilized preparations from both processes using TG-11 and TG/G-7, respectively, rely upon specific cleavage of disulfide cr oss-links under conditions which avoid the peptide bond cleavage of pr otein components. Amino acid analysis of the products solubilized with TG-II demonstrated the presence of cystine as well as lanthionine and cystine-residues of unknown origin.