Table 2.

SAXS data statistics

	Rg (Å)a	Dmax (Å)b	MMseq(kDa)c	MMexp(kDa)d	Vp (nm3)e	Ipnorm/Istdnorm,f	NSDg
10 mM EGTA	23.7±0.5	68.0±2.0	50.7	45.9±5	79±8	0.91±0.10	0.63±0.02
40 μM Ca2+	23.1±0.5	70.0±2.0	50.7	46.2±5	66±7	0.92±0.10	0.54±0.01

^aR_g determined from Grunier equation and data that satisfies Q_maxxR_g<1.3; similar values were obtained using the program GNOM (Svergun, 1992).

^bD_max was determined using the program GNOM (Svergun, 1992).

^cMM_seq is the molecular mass calculated from the primary sequence.

^d

MM_exp is the molecular mass calculated from the scattering data:

$${\mathit{MM}}_{\mathit{protein}}={\mathit{MM}}_{\mathit{lysozyme}}\times \frac{I_{\mathit{protein}}^o\times C_{\mathit{lysozyme}}}{I_{\mathit{lysozyme}}^o\times C_{\mathit{protein}}}$$

where MM_lysozyme is the molecular mass of lysozyme, I⁰ is the scattering intensity and C (mg/ml) is the protein concentration (Petoukhov and Svergun, 2006).

^eV_p is the excluded volume (Porod volume) calculated using PRIMUS (Konarev et al., 2003). Data with S>0.25 were excluded from the calculation (Petoukhov and Svergun, 2006; Porod, 1982).

^f

Normalized intensities for proteins (p) I^p_norm were calculated by

$$I_p^{\mathit{norm}}=(\frac{I^o}{C})/{\mathit{MM}}_{\mathit{seq}}$$

where I⁰ is the intensity calculated using the Guinier equation and C (mg/ml) is the protein concentration determined from its absorbance at 280 nm. Lysozyme served as a mono-dispersed protein standard (std). Ideally, the ratio I^p_norm/I^std_norm equals 1.00 (Jeffries et al., 2008; Taraban et al., 2008).

^gAfter superimposing the independently modeled envelopes, pair-wise normalized spatial discrepancy (NSD) values (Volkov and Svergun, 2003) were calculated as part of the DAMAVER routine. NSD values close to unity indicate good agreement between individual models.