TABLE 1.
Amide and carboxylate IR-absorptions for S-layers of the B. sphaericus strains JG-A12 and NCTC 9602
| Amide I components (cm−1) | Integral band intensity (%)
|
|
|---|---|---|
| JG-A12 | NCTC 9602 | |
| 1687 | 11 | 6 |
| 1676 | 5 | 5 |
| 1658 | 25 | 25 |
| 1635 | 39 | 48 |
| 1616 | 20 | 16 |
| Structure assignment | % | % |
| Helix | <18 (10–45) | <18 (9–44) |
| β-Strand | 33 (25–50) | 36 (24–52) |
| Turns | 10–20 (0–40) | 10–20 (0–40) |
| Random | >30 (0–40) | >30 (0–40) |
| Carboxylate vibrations | Native | Pd(II)-bound | Native | Pd(II)-bound |
| s COO− (cm−1) | 1400 | 1386−1410 | 1400 | 1386−1410 |
| as COO− (cm−1) | 1570 | 1560 | 1573 | 1572 |
| C=O stretch | 1720 | 1720 | 1720 | 1720 |
Secondary structure estimation is based on published assignments (27,29,53) as reviewed in Barth and Zscherp (52). The range of results of secondary structure predictions from primary structure-based algorithms (54–56) is shown in brackets. Integral intensities were transformed into relative amounts of secondary structure using absorptivity ratios of 0.6:1:1.5 for random coils and turns: α-helices, β-sheet (57).