α-RgIB: A Novel Antagonist Peptide of Neuronal Acetylcholine Receptor Isolated from Conus regius Venom

Table 1

Theoretical and experimental m/z values for the tryptic peptides obtained after the enzymatic digestion of α-RgIB.

Ions	[M + H]^+		[M + 2H]^2+		[M + 3H]^3+		Sequence
	Exp.	Theor.	Exp.	Theor.	Exp.	Theor.
A	1640.63^1,2	1639.839 ^1,2	820.82^1,2	820.423 ^1,2	547.55^1,2	547.282 ^1,2	TWEECCKNPGCR
B	1056.39^1,2	1055.180 ^1,2	528.70^1,2	528.094 ^1,2	—	x	TWEECCK
C	754.37	754.359	377.69	377.896	—	(252.125)	NNHVDR
D	619.30^2	619.298 ^2	—^3	(310.366) ^2,4	—	x	CRGQV
E	603.28^2	603.267 ^2	—	(302.137)	—	x	NPGCR
F	335.16^2	335.147 ^2	—	x^5	—	x	CR

1Acetylation (N-terminal, variable modification).
²Carbamidomethyl cysteine (fixed modification).
³Not detected.
⁴Not observed.
⁵Not expected.