Fibrous proteins of bovine hoof.

The matrix region of calf hoof was identified as the living precursor layer of the hardened hoof plate. Fibrous protein was isolated from the matrix with citrate buffer, pH. 2.65, while Tris buffer, pH. 9.5, with 8 M urea and a reducing agent was required to dissolve the cornified hoof. The purified matrix protein had a sodium dodecyl sulfate-polyacrylamide gel electrophoretic pattern similar to hoof plate and different from bovine epidermis. When the s-carboxymethyl derivatives of matrix, hoof plate, and hair proteins was compared by urea-polyacrylamide gel electrophoresis, they were identical, and different from that of epidermal protein. The matrix protein reacted with an antibody to hair fibrous protein. Cultured matrix keratinocytes appeared to be identical to cultured epidermal cells, pointing to the importance of the dermis in epidermal cell differentiation.