Properties of Protein Extracted as S-sulfonate Derivative from Irradiated Mink Hair

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We investigated the application of S-sulfonation process to characterize the extractable protein from irradiated mink hair. Intact hair sample was reduced with thiol (0.05M dithiothreitol, 0.05M Tris, 8M urea, pH9.45) at 4°C for 24hr. Then sodium sulfite and sodium tetrathionate were added to sulfonate the protein. After dialyzing, freezing and thawing, the extracted protein was successfully separated into two fractions; soluble fraction (Bs) and soluble fraction (Bp) by centrifugation. FTIR spectra, SDS-PAGE and amino acid composition of extracted protein demonstrated that Bs comes from matrix protein and Bp comes from microfibril protein. The irradiated hair showed remarkable decrease in protein extractability. SDS-PAGE pattern of the extract from irradiated hair demonstrated an almost complete disappearance of 45kDa and 60kDa bands with the unchanged band intensity at far lower position than 10kDa, and the existence of broad band below 14.5kDa. The amino acid composition of the extract from irradiated hair in Bp demonstrated a more remarkable increase in glycine, tyrosine and phenylalanine than in Bs. This suggests that the irradiation affects less heavily high-glycine-tyrosine component and mainly leaves the extraction in Bp fraction.