Table 1.
Guinier analyses of effect of peptide and calcium concentrations on particle size.
| Guinier |
||||||
|---|---|---|---|---|---|---|
| Peptide concentration |
[CaCl2] (mM) | Rg (Å) | Error | Io | Io/c | Number of molecules per particle |
| 2mg/ml | ||||||
| LRAP(+P) | 0 | 25.0 | 0.489 | 8.39 | 4.2 | 9 |
| 2.5 | 43.9 | 5.34E-02 | 73.12 | 36.6 | 47 | |
| LRAP(−P) | 0 | 48.0 | 5.34E-02 | 100.33 | 50.2 | 61 |
| 2.5 | 46.2 | 2.59E-02 | 85.87 | 42.9 | 55 | |
| 5mg/ml | ||||||
| 0 | 27.4 | 7.77E-02 | 20.304 | 4.06 | 11 | |
| LRAP(+P) | 0.76 | 35.5 | 5.32E-02 | 51.829 | 10.4 | 25 |
| 1.5 | 40.7 | 4.08E-02 | 115.14 | 23.0 | 37 | |
| 2.5 | 46.4 | 6.41E-02 | 165.03 | 33.0 | 56 | |
| 0 | 46.3 | 2.20E-02 | 230.17 | 46.0 | 55 | |
| LRAP(−P) | 0.76 | 49.5 | 2.80E-02 | 254.58 | 50.9 | 67 |
| 1.5 | 52.0 | 4.30E-02 | 286.57 | 57.3 | 78 | |
| 2.5 | 53.9 | 6.24E-02 | 302.99 | 60.6 | 87 | |
LRAP(−P) and LRAP(+P) exhibit similar radii of gyration (Rg) at 2 and 5 mg/mL. The Rg of LRAP(+P) is half of that of LRAP(−P) in the absence of calcium at pH~7.4. Rg and Io/c for LRAP(−P) increased slightly upon addition of up to 2.5 mM calcium, whereas marked and progressive increases in these parameters are observed in the presence of LRAP(+P), upon the addition calcium. Io is the extrapolated intensity at zero scattering angle and Io/c represents the Io values per unit peptide concentration. The estimated number of molecules calculated from the Rg is presented for comparison purposes.