Supplemental Data

Electron Capture Dissociation of Hydrogen-Deficient Species

Anastasia Kalli and Sonja Hess

Proteome Exploration Laboratory

Division of Biology

Beckman Institute

California Institute of Technology

Pasadena, CA 91125, USA

Figure S1.ECD spectra of the even electron (A) and hydrogen-deficient (B) precursors ions of neurotensin, pELYENKPRRPYIL-OH.Product ions intensities are significantly reduced following ECD of the hydrogen-deficient species.Product ions of the hydrogen-deficient species are one Dalton lighter compared to those of the even electron precursor ions. * = noise peaks

Figure S2.ECD spectra of the even electron (A) and hydrogen-deficient (B) precursors ions of angiotensin I, DRVYIHPFHL-OH.The abundances of product ions decreased in the ECD spectrum of thehydrogen-deficient species. In addition, several c- and z-type product ions detected for the [M + 2H]2+ species were absent in the ECD spectrum of the [M + H]2+● species.

Figure S3.Relative abundances of side chain and H2O/NH3 losses observed from the precursor ions in ECD of the [M + 2H]2+ and [M + H]2+●species of ACTH 1-10 (A), neurotensin (B), angiotensin I (C) and [Ile7]-angiotensin III (D). Abundances are normalized to the total abundances of all product ions (backbone bond cleavages, charge reduced species and neutral losses).

Figure S4. ECD spectra of the triply charged even electron (A) and hydrogen-deficient (B) precursors ions of angiotensin I, DRVYIHPFHL-OH. Both the intensities and the number of N-Cαbackbone bond cleavages were significantly suppressed in the ECD spectrum of the [M + 2H]3+●precursor ions. In addition, several b- and y-type product ions were only detected for the hydrogen-deficient species. * = noise peaks, ?= unidentified product ions, v2 = 2nd harmonic

Figure S5.Relative abundances of side chain and H2O/NH3 losses observed from the precursor ions in ECD of the [M + 3H]3+and [M + 2H]3+●species of neurotensin (A), and angiotensin I (B). Abundances are normalized to the total abundances of all product ions (backbone bond cleavages, charge reduced species and neutral losses).

Figure S6. Expanded views showing the peaks corresponding to theb2/b2 - 2H and c2’/c2●- H product ions observed in the ECDspectrum of the [M + H]2+● precursor ions of[Ile7]-angiotensin III.

Figure S7.Observed isotopic distribution of the charge reduced species following ECD of the [M + H]2+● precursor ions of[Ile7]-angiotensin III (A)and [M + 2H]3+●precursor ions of angiotensin I (B).For comparison, the theoretical isotopic distributions of the M+• and [M + H]+ species of [Ile7]-angiotensin III areshown in Figure S8.

Figure S8. Theoretical isotopic distribution of the M+● (A) and [M + H]+ (B) species of [Ile7]-angiotensin III.

Tables

Table S1A. Product ions observed in ECD of doubly protonated ACTH 1-10, SYSMEHFRWG-OH.

& = product ions were detected as a mixture of the odd and even electron species

Table S1B. Product ions observed in ECD of the doubly protonatedhydrogen-deficient speciesof ACTH 1-10, SYSMEHFRWG-OH.

& = product ions were detected as a mixture of the odd and even electron species

Table S2A. Product ions observed in ECD of doublyprotonatedneurotensin, pELYENKPRRPYIL-OH.

& = product ions were detected as a mixture of the odd and even electron species

Table S2B. Product ions observed in ECD of the doubly protonatedhydrogen-deficient species of neurotensin, pELYENKPRRPYIL-OH.

Table S3A. Product ions observed in ECD of doubly protonatedangiotensin I, DRVYIHPFHL.

.

& = product ions were detected as a mixture of the odd and even electron species

Table S3B. Product ions observed in ECD of the doubly protonatedhydrogen-deficient species of angiotensin I, DRVYIHPFHL.

Table S4A. Product ions observed in ECD of doubly protonated [Ile7]-angiotensin III, RVYIHPI-OH.

& = product ions were detected as a mixture of the odd and even electron species

Table S4B. Product ions observed in ECD of the doubly protonatedhydrogen-deficient species of [Ile7]-angiotensin III, RVYIHPI-OH

& = product ions were detected as a mixture of the odd and even electron species

Table S5A. Product ions observed in ECD of triply protonatedneurotensin, pELYENKPRRPYIL-OH.

& = product ions were detected as a mixture of the odd and even electron species

Table S5B. Product ions observed in ECD of the triply protonatedhydrogen-deficient species of neurotensin, pELYENKPRRPYIL-OH.

& = product ions were detected as a mixture of the odd and even electron species

Table S6A. Product ions observed in ECD of triply protonatedangiotensin I, DRVYIHPFHL.

& = product ions were detected as a mixture of the odd and even electron species

Table S6B. Product ions observed in ECD of the triply protonatedhydrogen-deficient species of angiotensin I, DRVYIHPFHL.

& = product ions were detected as a mixture of the odd and even electron species