Xaa is tyrosine or glutamine, w is an integer equal to 2 or 3, x is an integer from 1 to 3, y is an integer from 5 to 7, z is an integer equal to 1 or 2, and p is an integer such that the molecular weight of the protein is between 10 and 400 kDa, to skin, nails, hair or mucous membranes.