Table 1.

Summary of obtained parameters ^a.

Compound			E°′SeSe [mV] b	v0BPIns [μM min−1] c	RHEL → NHEL		4SS → NHEL d
	Gly (or Pro)	Xaa			Amax [%] d	k [×10−3 min−1] e	Amax [%] d	t50 [min] f
1g:	None	None	−368 ± 5	1.25 ± 0.03	81.1 ± 0.7	27.6 ± 0.6	59.4 ± 0.9	109 ± 4
2ag:	None	His	−304 ± 7	2.45 ± 0.06	83.0 ± 1.3	32.7 ± 0.7	60.9 ± 0.7	74 ± 8
3:	Pro	His	−289 ± 8 h	ND i	82.8 ± 0.7 h	32.8 ± 1.4 h	60.1 ± 1.1	122 ± 17
4a:	Gly	His	−356 ± 2 h	2.00 ± 0.14	82.5 ± 1.0 h	30.6 ± 0.9 h	60.3 ± 0.6	127.0 ± 26.2
2bg:	None	Lys	−352 ± 2	1.94 ± 0.08	82.7 ± 3.2	29.8 ± 0.6	59.1 ± 0.1	107 ± 10
4b:	Gly	Lys	−352 ± 1	2.14 ± 0.03	83.2 ± 0.1	31.3 ± 1.8	53.7± 1.6	167 ± 9
2c g:	None	Arg	−353 ± 1	2.64 ± 0.06	79.8 ± 0.4	30.9 ± 1.2	57.7 ± 0.1	105 ± 5
4c:	Gly	Arg	−331 ± 3	2.65 ± 0.05	81.4 ± 1.0	35.4 ± 1.8	72.1 ± 1.4	54 ± 9
2dg:	None	Ala	−340 ± 2	2.22 ± 0.07	80.6 ± 0.3	28.3 ± 1.4	59.0 ± 0.7	101 ± 5
4d:	Gly	Ala	−361 ± 2 h	2.12 ± 0.05	83.5 ± 2.1 h	23.5 ± 2.3 h	62.8 ± 4.2	91 ± 6
No compound g			−	0.36 ± 0.02	78.6 ± 1.5	17.9 ± 0.6	55.2 ± 1.6	>240

^a All data are shown as mean ± SEM (n = 3). ^b Diselenide reduction potentials were estimated by following a method reported in the literature [16]. ^cInitial velocity estimated from Figure S3 for catalytic SS-reduction of bovine pancreatic insulin (BPIns). ^d Maximal enzymatic activity of HEL recovered in the folding experiments. ^e Apparent rate constant obtained by fitting the experimental data (Figure 6a). ^f Time required to reach 50% recovery of HEL enzymatic activity in the refolding of 4SS. ^g,h Data reported in [18,28], respectively. ⁱ Not determined.