Facile preparation of molybdenum (VI) oxide – modified graphene oxide

nanocomposite for specific enrichment of phosphopeptides

Haofan Sun, a Quanqing Zhang, b Lei zhang, a Weibing Zhang, *, a and Lingyi zhang *, a

a Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry & Molecular

Engineering, East China University of Science and Technology, Shanghai 200237, China.

b Department of Chemistry and Institutes of Biomedical Sciences, Fudan University, Shanghai

200433, China.

zhanglingyi@ecust.edu.cnweibingzhang@ecust.edu.cn

ContentsFigure S1. Size distribution of GO/MoO3 by the hydrothermal reaction condition of 160°C for 24 h. -----------------------------------------------------------------------------------2Figure S2. Size distribution of MoO3 on the nanocomposites by the hydrothermal reaction condition of (a) 160°C for 24 h and (b) 180°C for 20 h. -------------------------2Figure S3. TEM images of MoO3/GO fabricated by contrast condition (hydrothermal reaction, 180°C, 20 h) in different sizes. ------------------------------------------------------3Figure S4. XPS spectra of (a) wide scan of GO and GO/MoO3, (b) Mo 3d spectrum, (c) C1s spectrum, (d) O1sspectrum of GO and (e) O1s spectra of GO/MoO3----------------3Figure S5. EDS spectrum of MoO3/GO nanocomposites. ---------------------------------4Figure S6. Zeta-potential value of (a) GO and (b) GO/MoO3 nanocomposites in pure water (pH=7.0). ----------------------------------------------------------------------------------4Figure S7. MALDI-TOF mass spectra of different concentration of -casein digest after enrichment by MoO3/GO nanocomposites. --------------------------------------------5Figure S8. Comparison of phosphopeptides enrichment capacity by different amount of GO/MoO3 from tryptic digests of -casein (1.5 g). ------------------------------------5Table S1. List of phosphopeptides identified from tryptic digest of -casein after enriched by MoO3/GO nanocomposites. -----------------------------------------------------6Table S2. Signal-to-noise ratios in the recovery and enrichment cycles. ----------------6Table S3. List of phosphopeptides from tryptic digest of proteins extracted from nonfat milk after enriched by MoO3/GO nanocomposites. -----------------------------------------7

Table S4. List of phosphopeptides from diluted human serum after enriched by MoO3/GO nanocomposites. ------------------------------------------------------------------------------------7

Figure S1. Size distribution of GO/MoO3 by the hydrothermal reaction condition of 160°C for 24 h.

Figure S2. Size distribution of MoO3 on the nanocomposites by the hydrothermal reaction condition of (a) 160°C for 24 h and (b) 180°C for 20 h.

Figure S3. TEM images of MoO3/GO fabricated by contrast condition (hydrothermal reaction, 180°C, 20 h) in different sizes.

Figure S4. XPS spectra of (a) wide scan of GO and GO/MoO3, (b) Mo 3d spectrum, (c) C1s spectrum, (d) O1s spectrum of GO and (e) O1s spectra of GO/MoO3.

Figure S5. EDS spectrum of MoO3/GO nanocomposites.

Figure S6. Zeta-potential value of (a) GO and (b) GO/MoO3 nanocomposites in pure water (pH=7.0).

Figure S7. MALDI-TOF mass spectra of different concentration of -casein digest after enrichment by MoO3/GO nanocomposites. (a) 10 fmol; (b) 5 fmol; (c) 2 fmol; (★) phosphopeptides and (●) dephosphorylated peptides.

Figure S8. Comparison of phosphopeptides enrichment capacity by different amount of GO/MoO3 from tryptic digests of -casein (1.5 g).

Table S1. List of phosphopeptides identified from tryptic digest of -casein after enriched by MoO3/GO nanocomposites.

Peak label

Number of phosphoryl

groups

Peptide sequence Observed m/z

1 1 KNMAINP[pS]KENL 1196.51 1 FQ[pS]EEQQQTEDELQDK 2061.62 4 NVPGEIVESL[pS] [pS] [pS]EE[pS]ITR 2352.63 1 FQ[pS]EEQQQTEDELQDKIHPF 2555.84 4 RELEELNVPGEIVE[pS]L[pS][pS]

[pS]EESITR3121.9

Table S2. Signal-to-noise ratios in the recovery and enrichment cycles.

conditionNumber of

phosphopeptidesS/N ratio

range averageRecovery - 2 366.18-402.21 384.20

-casein

1 pmol/mL 5 438.20-3057.31 1514.8310 fmol/mL 4 166.76-762.93 473.755 fmol/mL 4 49.26-138.96 90.952 fmol/mL 3 4.95-13.62 8.141 fmol/mL 4 4.98-28.06 20.52

-casein and BSA mixture

1:100 5 252.01-1687.83 762.971:500 5 43.13-900.81 279.21:1000 5 24.10-597.47 219.36

Nonfat milk - 13 27.14-660.71 154.66Human serum - 4 400.77-993.37 615.38

Table S3. List of phosphopeptides from tryptic digest of proteins extracted from nonfat milk after enriched by MoO3/GO nanocomposites.

Peak label

Number of phosphoryl

groups

Peptide sequence Observed m/z

1 KNMAINP[pS]KENL 1197.0 1 TVD[Mo]ME[pS]TEVF 1253.1 1 TVDME[pS]TEVFTK 1466.8 1 TVD[Mo]E[pS]TEVFTK 1483.0 2 EQL[pS]T[pS]EENSKK 1539.0 1 VPQLEIVPN[pS]AEER 1660.1 2 DIG[pS]E[pS]TEDQAMEDIK 1927.6 3 NANEEEYSIG[pS][pS][pS]EEAEVATEEVK 2926.8 2 FPQ[pY]LQ[pY]LYQGPIVLNPWDQVKR 3025.8 1 FQ[pS]EEQQQTEDELQDK 2062.8 1 FQ[pS]EEQQQTEDELQDKIHPF 2556.4 4 RELEELNVPGEI[pS]L[pS][pS][pS]EESITR 3122.9

Table S4. List of phosphopeptides from diluted human serum after enriched by MoO3/GO nanocomposites.

Peak label

Number of phosphoryl

groups

Peptide sequence Observed m/z

HS1 1 D[pS]GEGDFLAEGGGV 1388.92 HS2 1 AD[pS]GEGDFLAEGGGV 1459.96 HS3 1 D[pS]GEGDFLAEGGGVR 1545.03 HS4 1 AD[pS]GEGDFLAEGGGVR 1616.04