<prompt> Keratin in skin is softer than keratin in nail because keratin in skin has:Less number of disulphide bondsLess number of salt bridgesHigh sodium contentDifferent affinity for water  <response>: A i.e. Less number of disulphide bondsKeratin in skin is softer than keratin in nail, horn hooves because skin keratin has less number of disulfide bondsQ between Cys residues of adjacent polypeptide chains. 