S-sulfokeratein is prepared through S-sulfonation after the cleavage of disulfide bonds in keratin using ditiothreitol in urea. S-sulfokeratein is composed of two fractions, matrix and microfibril components, and S-sulfokeratein from the matrix component (Bs) can regenerate disulfide bonds. In this study, the effects of Bs and partially reduced Bs on type I collagen self-assembly and properties of reconstructed Bs- or partially reduced Bs-collagen gel were investigated. It was proved that collagen self-assembly was accelerated by the increased amount of added Bs, but partially reduced Bs with 10 mg DTT/100 mg Bs (Bs-10) did not affect the ratio of collagen self-assembly. The mechanical strength of Bs-collagen gel proved to be lower than control, but that of Bs-10-collagen gel was times higher than that of control.