Supporting Information

Investigation of bn-44 Peptide Fragments Using High Resolution MassSpectrometry and IsotopeLabeling

Bing Wang1†, Jiayi Yu2†, Huixin Wang1, Zhonglin Wei1,Xinhua Guo1*, Zhaohui Xiao1, Zhoufang Zeng1, Wei Kong2*

1College of Chemistry, JilinUniversity, Changchun, China 130012,

2TheState Engineering Laboratory of AIDS Vaccine, JilinUniversity, ChangchunChina 130012,

†These two authors contributed equally to this work.

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Dr. Xinhua Guo, Professor

Address: TangaoqingBuilding, 2699 Qianjin Street, Changchun,China, 130012

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Dr. Wei Kong, Professor

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Figure S1.MS spectrumofthe DhHP-6 using an ion trap mass spectrometer

Figure S2.MS3spectra of (a) the b2+ ; (b) the [b2+H]2+; (c) the b3+ and (d) the b4+using ion trap mass spectrometer

Figure S3.MS/MS spectra of the DhHP-6 (a) M2+,(b) M3+and inset : extending MS/MS spectra of M2+ around (c) b2+ (d) b3+ and (d) b4+by using an ESI-Q-TOF mass spectrometerat m/z 3.0 of isolation width

Note: m/z values for the doubly charged ions (the same as that from Figure S4)

m/z / ions / m/z / ions
363.6 / [a2+H]2+ / 419.1 / [b3+H-H2O]2+
377.6 / [b2+H]2+ / 428.2 / [b3+H]2+
405.1 / [a3+H-H2O]2+ / 454.7 / [a4+H-H2O]2+
414.2 / [a3+H]2+ / 463.7 / [a4+H]2+

Figure S4. MS/MS spectrum of (a) the ion isolationat 614.0 with anuni-resolution width and inset: extending of the spectrum in m/z range of (b) 700-760, (c) 800-860 and (d) 900-960 by using an ESI-Q-TOF mass spectrometer

Note: theoretical m/z values of doubly charged ions at 614.8 (isotope peak at 615.3), experiment of the 614.0 withuni-resolution allow 614.8 pass and avoid 615.3.

Figure S5.MS/MS spectrum of (a) the singly charged NH2-DhHP-6 and inset: extending spectra in m/z range of (b) 700-760, (c) 800-860 and (d) 900-960 by using an ESI-Q-TOF mass spectrometer

Figure S6. MS/MS spectrumof (a) the singly charged DpHP-6 ion and inset: extending spectra in m/z range of (b) 650-710, (c) 750-810 and (d) 850-910 by using an ESI-Q-TOF mass spectrometer

Table S1. Total (Etotal, Hartree) energies and zero-point corrections of the most stable neutral and protonated forms calculated at B3LYP/6-31+G(d,p) level

Etot+ ZPE/
Hartree / ZPE
Hartree / ΔEtot+ ZPE/
kcal mol-1
Best neutral / -1303.656758 / 0.518487 / 0
Protonation site
N1 / -1304.005008 / 0.531546 / 218.53
N2 / -1304.051443 / 0.531777 / 247.67
N3 / -1034.006777 / 0.531824 / 219.64
N4 / -1304.052311 / 0.531840 / 248.21

Note: The PA of Lys and Arg reported by Paizs with their DFT values are 237.3kcalmol-1and 253.3 kcalmol-1, respectively.

The most stable neutral form:

The protonated form protonated at imine-N4