Supporting Information

Investigation of bn-44 Peptide Fragments Using High Resolution Mass Spectrometry and Isotope Labeling

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

1College of Chemistry, Jilin University, Changchun, China 130012,

2The State Engineering Laboratory of AIDS Vaccine, Jilin University, Changchun China 130012,

†These two authors contributed equally to this work.

Address reprint requests to:

Dr. Xinhua Guo, Professor

Address: Tangaoqing Building, 2699 Qianjin Street, Changchun, China, 130012

Phone number: 86-431-85166389

Fax number: 86-431-85166389

Email:

Dr. Wei Kong, Professor

Email:


Figure S1. MS spectrum of the DhHP-6 using an ion trap mass spectrometer


Figure S2. MS3 spectra 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 spectrometer at 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 isolation at 614.0 with an uni-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 with uni-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 spectrum of (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 237.3 kcal mol-1 and 253.3 kcal mol-1, respectively.

The most stable neutral form:

The protonated form protonated at imine-N4