<prompt> Keratin of skin is softer than keratin in nail because keratin in skin hasLess number of disulphide bridgesLess number of salt bridgesHigh sodium contentDifferent affinity for water  <response>: Keratin in skin is softer than keratin in nail, horns because of lesser disulphide linkages between cysteine residues Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 489 