Table 1.
Amino acid composition (as residues per 100 residues) of human nail, hair and stratum corneum [19, 28].
| Amino acid | pI a | Nail (%) | Hair (%) | Stratum corneum (%) |
|---|---|---|---|---|
| Lysine | 9.74 | 3.1 | 2.5 | 4.2 |
| Histidine | 7.59 | 1.0 | 0.9 | 1.5 |
| Arginine | 10.76 | 6.4 | 6.5 | 3.8 |
| Aspartic acid | 2.77 | 7.0 | 5.4 | 7.9 |
| Threonine | 5.60 | 6.1 | 7.6 | 3.0 |
| Serine | 5.68 | 11.3 | 12.2 | 13.6 |
| Glutamic acid | 3.22 | 13.6 | 12.2 | 12.6 |
| Proline | 6.30 | 5.9 | 8.4 | 3.0 |
| Glycine | 5.97 | 7.9 | 5.8 | 24.5 |
| Alanine | 6.00 | 5.5 | 4.3 | 4.4 |
| Valine | 5.96 | 4.2 | 5.5 | 3.0 |
| Methionine | 5.74 | 0.7 | 0.5 | 1.1 |
| Isoleucine | 6.02 | 2.7 | 2.3 | 2.7 |
| Leucine | 5.98 | 8.3 | 6.1 | 6.9 |
| Tyrosine | 5.66 | 3.2 | 2.2 | 3.4 |
| Phenylalanine | 5.48 | 2.5 | 1.7 | 3.2 |
| Half-cystine | 5.07 | 10.6 | 15.9 | 1.2 |
a
pI is the isoelectric point of the individual amino acids.