Table 2.

SAXS data fitting results from the software OLIGOMER for the estimate of tetramer, dimer, and monomer percentages of wt-AXH, A567G-AXH, and I580A-AXH at different sample concentrations

	Concentration (mM)	Monomer %	Dimer %	Tetramer %	High order oligomer, %	χ2
WT-AXH	1.35	21	39	26	14	1.56
	0.67	27	42	20	11	1.28
	0.33	32	45	15	8	1.22
	0.17	38	45	10	7	0.90
	0.08	41	46	7	6	0.91
	0.04	43	45	7	5	0.98
WT-AXH (fresh)	1.35	28	55	17	none	1.76
	0.67	32	55	13	none	1.38
	0.33	30	63	7	none	1.23
	0.17	27	73	0	none	1.15
	0.08	25	75	0	none	1.33
	0.04	30	70	0	none	1.12
A567G-AXH	1.35	37	42	21	none	1.53
	0.67	46	40	14	none	1.14
	0.33	56	33	11	none	1.03
	0.17	66	26	8	none	1.00
	0.08	75	16	9	none	0.98
	0.04	81	11	8	none	0.98
I580A-AXH	1.35	55	39	3	3	1.51
	0.67	61	34	3	2	1.16
	0.33	68	26	4	2	1.01
	0.17	75	18	4	3	0.92
	0.08	80	14	4	2	0.91
	0.04	80	15	3	2	0.90

In the case of wt-AXH and I580A-AXH, the presence of higher oligomers (i.e., extended octamers and hexadecamers) are necessary to fit the low-angle region. The label Wt-AXH (fresh) corresponds to the freshly produced batch of WT-AXH sample.