Keratin in skin is softer than keratin in nail because keratin in skin has -
The extent of keratin hardness depends on the number of disulfide bonds/sulfur content. The more the number of disulfate bonds, the harder the keratin is.
Keratin in skin is softer than keratin in nails because it has less number of disulfide bonds.
Less number of disulphide bonds
Less number of salt bridges
High sodium content
Different affinity for water