The chaperone-like activities, substrate binding and oligomerization capabilities of full-length and truncated AlIbpA proteins^a.

AlIbpA variant	Protein structure	bΔTm 50, °C		cInsulin binding	dADH binding KD, μM	eDistribution of various oligomeric fractions, %
		eIbpA	fIbpA + insulin			I peak	II peak	1×-4×-mers
Full length		0g	+5 ± 0.8	++	1.6 ± 0.3	23 ± 10.3	74 ± 17.8	3 ± 0.2
ΔN12		+3 ± 0.3*	+10 ± 2.3*	+	3.5 ± 1.1	88 ± 17.1	10 ± 1.1	3 ± 0.1
ΔN25		+3 ± 0.4*	+10 ± 2.1*	++	2.2 ± 0.7	77 ± 21.3	12 ± 2.4	11 ± 2.1
N11N12		+5 ± 0.8*	+11 ± 2.4*	++	0.5 ± 0.1	8 ± 1.7	88 ± 12.2	4 ± 0.7
ΔC14		−7 ± 0.6*	−3±1.0*	++	0.7 ± 0.1	7 ± 4.1	86 ± 23.4	7 ± 2.3
ΔN12C14		−5 ± 0.7*	−6±1.2*	—	NA	1 ± 0.1	86 ± 22.8	14 ± 10.3
ΔN25C14		−13 ± 2.2*	−9±1.1*	+	NA	1 ± 0.2	50 ± 13.5	49 ± 10.3
SEP		−2 ± 0.1	+2 ± 0.2*	—	NA	18 ± 4.4	56 ± 7.8	26 ± 5.9
SEPΔN12		−1 ± 0.3	+3 ± 0.5	+	7.2 ± 1.4	2 ± 0.8	59 ± 10.1	39 ± 9.9
SEPΔN25		+1 ± 0.2	+5 ± 0.9	++	3.2 ± 0.5	69 ± 15.5	23 ± 3.2	8 ± 2.0

^a* – denotes statistically significant difference with full-length AlIbpA.

^bDetermined by measuring the sypro-orange fluorescence.

^cDetermined as ratio of AlIbpA and insulin bands density on in vitro pull-down assay SDS-PAGE (see ESI Fig. S5): “−” – no interaction, “+” – 1 : 1 ratio, “++” 1 : 2 and higher.

^dCalculated from the ADH-to-AlIbpA surface binding curve slopes obtained with SPR (NA – not available because of no interaction).

^eCalculated as fractions of areas under the peaks on the elution profile.

^fThe T_{m 50} value of full-length AlIbpA is accepted as zero.

^gThe T_{m 50} value of insulin in absence of full-length AlIbpA is accepted as zero.