Table 1. Chemical and Mass Spectrometric Parameters of T20K Peptides.

name	specification	molecular formula	molecular weight [g/mol](monoisotopic)	[M + H]+(theoretical)	[M + 3H]3+
T20K	cyclic native oxidized	C119H184N36O38S6	2917.19	2918.20	973.40
cyclic reduced T20K	cyclic cysteine reduced	C119H190N36O38S6	2923.24	2924.24	975.42
T20K-Acm	-S-acetamide	C131H208N42O44S6	3265.36	3266.37	1089.46
T20K-S-methyl	-S-S-methyl	C125H202N36O38S12	3199.16	3200.17	1067.39
T20K-Nem	-S-(N-ethyl-maleimide)	C155H232N42O50S6	3673.52	3674.53	1225.51
1SS variant	cystine knot truncated; four S-acetamides	C127H200N40O42S6	3149.31	3150.31	1050.78
2SS variant	cystine knot truncated; two S-acetamides	C123H192N38O40S6	3033.25	3034.26	1012.09
T20K-(Cys to Ala)	all cysteines changed to alanine	C119H192N36O39	2731.40	2732.41	911.47
3SS variants of T20K	cyclic non-native oxidized cystine knot	C119H184N36O38S6	2917.19	2918.20	973.40
linear folded T20K variant	linear (Arg|Asn) native folded	C119H186N36O39S6	2935.20	2936.21	979.41
T20K-CF	Lys20-ε-amine labeled carboxyfluoresceine	C140H192N36O44S6	3275.63	3276.64	1092.89