Table 2.

Sedimentation equilibrium results for syt249–421 (molecular mass of 19,853 Da) and syt261–421 (molecular mass of 18,395 Da)

Single ideal species model
Sample	Molecular mass, Da	Standard deviation of fit
apo-syt249–421	26,608	6.36  × 10−3
syt249–421 + 110 μM Ca2+	24,435	5.36  × 10−3
syt249–421 + 550 μM Ca2+	26,108	7.23  × 10−3
syt249–421 + 1.1 mM Ca2+	26,273	4.43  × 10−3

Single non-ideal species model
Sample	Molecular mass, Da	Standard deviation of fit
apo-syt249–421	15,971	2.54  × 10−3
syt249–421 + 110 μM Ca2+	16,734	3.01  × 10−3
syt249–421 + 550 μM Ca2+	15,202	2.78  × 10−3
syt249–421 + 1.1 mM Ca2+	19,232	3.24  × 10−3

Single ideal species model
Sample	Molecular mass, Da	Standard deviation of fit
apo-syt261–421	19,969	6.20  × 10−3
syt261–421 + 110 μM Ca2+	19,186	6.66  × 10−3
syt261–421 + 550 μM Ca2+	21,637	3.68  × 10−3
syt261–421 + 1.1 mM Ca2+	21,902	6.30  × 10−3

Single non-ideal species model
Sample	Molecular mass, Da	Standard deviation of fit
apo-syt261–421	17,124	3.63  × 10−3
syt261–421 + 110 μM Ca2+	18,204	3.81  × 10−3
syt261–421 + 550 μM Ca2+	17,756	3.43  × 10−3
syt261–421 + 1.1 mM Ca2+	20,811	6.31  × 10−3

Both truncated versions of the protein are best fit using a single non-ideal species model and are monomeric in solution.