1

Supporting Information for the article:

Tandem mass spectrometry and infrared spectroscopy as a help to identify peptide

oxidized residues

D. Scuderi,*a M. T. Ignasiak a, b, X. Serfaty a, P.de Oliveiraa and C. Houée Levina

Figure 1SI: CID-MS2 fragmentation mass spectrum of (GS-Me)H+ (m/z 322).

100 200 300 400

0

1x107

2x107

229 247

130

176

193

I (a

.u.)

m/z

322

Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics.This journal is © the Owner Societies 2015

2

Figure 2SI: CID-MS2 fragmentation mass spectrum of GS-Me(O)H+ (m/z 338).

100 200 300 400

0,0

5,0x105

1,0x106

1,5x106

2,0x106

2,5x106

3,0x106

3,5x106

145 256

209

274

308320

I (a

.u.)

m/z

338

3

Figure 3SI: CID-MS2 fragmentation mass spectrum of GS-Me(O)2H+ (m/z 354).

100 200 300 400

0

1x105

2x105

3x105

4x105

5x105

6x105

279

225

I(a

.u)

m/z

354

4

Figure 4SI: CID-MS2 fragmentation mass spectrum of (GS-Me)H+-CO2 (m/z 278).

100 200 300 400

0,0

2,0x105

4,0x105

6,0x105

8,0x105

1,0x106

130

147

193

261

I (a

.u.)

m/z

278

5

Figure 5 SI: CID-MS2 fragmentation mass spectrum of (GS-Me)H+-H2 (m/z 320).

100 200 300 400

0,0

5,0x105

1,0x106

1,5x106

2,0x106

191

308

I(a

.u.)

m/z

320

6

Figure 6SI: Mass spectra of non-irradiated (a) and irradiated Trp-Met (b) (irradiation dose 800 Gy).

200 300 400 500 600

0,0

4,0x107

8,0x107

a)

319

336

Inte

nsit

y (

a.u

.)

m/z

200 300 400 500 600

0,0

2,0x107

4,0x107

6,0x107

352

b)

319

336

Inte

nsit

y (

a.u

.)

m/z

7

Figure 7SI: Mass spectra of non-irradiated (a) and irradiated Met-Trp (b) (irradiation dose 900

Gy).

250 300 350 400 450 500

0,0

2,0x107

4,0x107

6,0x107

8,0x107

1,0x108

364

336

358

Inte

ns

ity

(a

.u.)

m/z

392

a)

250 300 350 400 450 500

0,0

5,0x106

1,0x107

1,5x107

2,0x107

2,5x107

368

Inte

ns

ity

(a

.u.)

m/z

392364

352

336

b)

8

200 300 400 500 600

0,0

2,0x106

4,0x106

6,0x106

8,0x106

319

I (a

.u.)

m/z

336

Figure 8SI: CID-MS2 fragmentation mass spectrum (Trp-Met)H+ (m/z 336).

9

200 300 400 500 600

0,0

2,0x106

4,0x106

6,0x106

8,0x106

1,0x107

I(a

.u.)

m/z

352

335

288

271

Figure 9SI: CID-MS2 fragmentation mass spectrum of (Trp-Met)O2H+ (m/z 352).

10

Figure 10SI: CID-MS2 fragmentation mass spectrum of (Met-Trp)H+ (m/z 336).

200 300 400 500

0,00

2,50x106

5,00x106

I (a

.u.)

m/z

318

288

271

336205

188

11

150 200 250 300 350 400

0

1x106

2x106

3x106

I (a

.u.)

m/z

352

334

316

306

288

270

260

243

221

Figure 11SI: CID-MS2 fragmentation mass spectrum of (Met-Trp)OH+ ( m/z 352).

12

Figure 12SI: CID-MS2 fragmentation mass spectrum of (Met-Trp)O2H+ (m/z 368).

150 200 250 300 350 400 450 500

0,0

5,0x105

1,0x106

1,5x106

237

276

286304

322

332350

I(a

.u.)

m/z

368

13

Figure 13SI: Mass spectrum of non-irradiated (a) and irradiated (b) Trp (irradiation dose 900 Gy).

50 100 150 200 250 300 350 400 450 500

0,0

2,0x106

4,0x106

409

Inte

ns

ity

(a

.u.)

m/z

205

a)

50 100 150 200 250 300 350 400 450 500

0,0

5,0x106

1,0x107

253269

409

237221

188

Inte

ns

ity

(a

.u.)

m/z

205

b)

14

Table 1SI. Most intense peaks in the CID-MS2 fragmentation mass spectra of the products of GS-Me.

.

Compound m/z, z=+1

(GS-Me)H+-CO2

(GS-Me)H+-H2

(GS-Me)H+

278 (parent ion)

261 (-NH3)

193(y2)

147 (y2-H2O-CO)

130 (y2-H2O-CO-NH3 )

320 (parent ion)

308 (-H2O)

191 (y2)

322 (parent ion)

247(b2)

229 (b2-H2O)

193(y2)

176 (y2-NH3)

130 (b1 ou y2-17-H2O-CO)

338(parent ion)

320(-H2O)

274(-CH3SHO)

256(-H2O-CH3SOH)

209 (y2)

145 (y2-CH3SOH)

354 (parent ion)

279 (b2)

225 (y2)

208 (y2- NH3)

130 (b1)

(GS-Me)OH+

(GS-Me)O2H+

15

Table 2SI. Most intense peaks observed in the CID-MS2 fragmentation mass spectra of the products of

oxidation of Trp-Met.

Compound m/z, z=+1

(Trp-Met)H+

(Trp-Met)OH+

336 (parent ion)

319 (Trp-Met)H+-NH3

352 (parent ion)

335 (Trp-Met)OH+-NH3

288 (Met-Trp)OH+-CH3SOH

271 (Met-Trp)OH+-NH3-CH3SOH

16

Table 3SI. Most intense peaks observed in the CID-MS2 fragmentation mass spectra of the products

of oxidation of Met-Trp.

Compound m/z, z=+1

(Met-Trp)H+

(Met-Trp)OH+

(Met-Trp)O2H+

336 (parent ion)

318 (Met-Trp)H+-H2O

288 (Met-Trp)H+-CH3SH

271 (Met-Trp)H+-NH3

205 (y)

188 (y-NH3)

352 (parent ion)

334 (Met-Trp)OH+-H2O

316 (Met-Trp)OH+-2H2O

306 (Met-Trp)OH+-H2O-CO

288 (Met-Trp)OH+-CH3SOH

270 (Met-Trp)OH+-H2O -CH3SOH

243 (Met-Trp)OH+-H2O -CH3SOH-NH3

221 (y)

368 (parent ion)

350 (Trp-Met)O2H+-H2O

332 (Trp-Met)OH+-2H2O

304 (Trp-Met)O2H+-CH3SOH

286 (Trp-Met)OH+-CH3SOH-H2O

276 (Trp-Met)OH+-CH3SOH-CO

237 yO2

17

m/z, z=+1 compound

237 (Trp)O2H+

220 (Trp)O2H+-NH3

219 (Trp)O2H+-H2O

202 (Trp)O2H+-NH3-H2O

192 (Trp)O2H+ -NH3-CO

174 (Trp)O2H+ -NH3-CO-H2O

Table 4SI: Most intense peaks observed in the CID-MS2 fragmentation mass spectrum of ions at m/z

237 and their attribution.

18

Scheme 1SI: Schematic representation of y2 fragments for each oxidation product of GS-Me

according the Roepstorff-Fohlman nomenclature.

Y2

2 3

4 5

1

Y2

Y2

Y2

Y2

Y2

b)

19

Scheme 2SI: Structures of 5hydroxytrypthophan (a) and oxindolylalanine (b) corresponding to the

addition of an oxygen atom to the tryptophan.

a) b)