Table 1.

Recovery of iron reduction activity in protein fractions:

Sample	Protein Concentration (mg/mL)	Iron Reduction Activity (nmol Fe(II) formed/minute)	Specific Activity (nmol Fe(II) formed/mg protein/minute)
Soluble (S) fraction	5.45	2.07	12.64
Insoluble (IS) fraction	1.21	0.81	22.42
S Peak 1: SAX 16′	<0.125	0.79	>210.82
S Peak 1: SAX 16′ SEC 9.5′	<0.125	0.50	>132.14
S Peak 2: SAX 31–32′	<0.125	0.19	>50.09
S Peak 2: SAX 31–32′ SEC 10.5′	<0.125	0.16	>43.94
IS Peak 1: SAX 31′	<0.125	0.08	>22.16

Specific iron reduction activity is calculated for protein fractions using the iron reduction activity assay. Nearly twice the specific iron reduction activity was recovered in the total insoluble fraction versus the soluble fraction. Specific activities described as “>” values were limited in precision due to below detect protein concentrations as determined by Bradford assay. SAX= anion exchange chromatography. SEC= size exclusion chromatography.