Table 1.
Assignment, spectral positions, and content of amide I secondary structures probed by FTIR spectroscopy
| HEWL (1% EtOH) |
Insulin (1% EtOH) |
Assignment (39, 40, 41, 42, 43,45,58) | ||||||
|---|---|---|---|---|---|---|---|---|
| Freshly prepared |
Fibril |
Freshly prepared |
Fibril |
|||||
| (±2 cm−1) | (%) | (±2 cm−1) | (%) | (±2 cm−1) | (%) | (±2 cm−1) | (%) | |
| 1616 | 10.5 | 1616 | 20 | 1615 | 10 | 1616 | 31 | side chains/β-sheets |
| – | – | 1626 | 31 | 1631 | 8 | 1630 | 28 | intermolecular β-sheets |
| 1641 | 12.5 | – | – | 1648 | 32 | 1645 | 16 | unordered |
| 1654 | 58 | 1651 | 3 | 1656 | 40 | 1654 | 8 | α-helix |
| – | – | 1666 | 30 | – | – | 1668 | 12 | irregular helix/loops |
| – | – | 1677 | 10 | 1678 | 3 | – | – | turns |
| 1683 | 19 | 1695 | 2 | 1691 | 6 | 1695 | 5 | β-sheets |
The assignment of amide I secondary structures is made on the basis of the minima found in the second-derivative spectra of the freshly prepared and of the fibril solutions of HEWL and insulin (1% EtOH). The spectral position and the content of each protein secondary structure is reported as well. The error estimated for each area is approximately of 2%.