CHAPTER 17 • Characterization of Marine Toxins with LC-ESI-MS
335
a
M+
M+
[M+2H]2+
1789.6
894.7
' i j I , .1.",
,
[M + 2H]2+ 100 I 143
1
7.2
100 719.6
75
j 75
~g l - - - , , - - - ~ ' ' ' ' ' ' ' ' ' . * - ' ' I ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' f
. 1 50
1 200 1300 1 400 1 500 1 600
!
100
.~ 75
III
c
b
Molecular weight
25
1437.8 [M+H]+
\
O~~--------~--~~~
800
1000 1200
m/z
1400 1600
S 50
.5
.~ 25
III
~
0
1000
Gloxidized
/
Gl 2-phenylmaleimide
0.0
60.0
360.0387.8
YS
A2
1700
1800
1900
Molecular weight
[M+H]+
1787.5
1500
2000
m/z
Fig. 17.10. a LC-ESI -MS chromatogram of partially reduced and alkylated GI a-conotoxin. Stepwise
reduction and alkylation were carried out with tris(2-carboxyethyl)phosphine and N -phenylmaleimide,
respectively. Inset: ESI mass spectra of original and derivatized conotoxin; b MS-MS daughter ion spectrum of reduced and alkylated GI a-conotoxin molecular ion. In the interpretation scheme, amino
acids are represented by conventional one-letter symbols; B indicates N-phenylmaleimide-substituted
cysteine (reprinted with permission from Jones et aI. 1996