Correlation between the charge of proteins in solution and in the gas phase investigated by protein charge ladders, capillary electrophoresis, and electrospray ionization mass spectrometry

Journal Article · Thu Dec 17 04:00:00 EST 1998 · Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical

DOI:https://doi.org/10.1021/jp980768u· OSTI ID:316055

Carbeck, J D; Gao, J; Smith, R D; Whitesides, G M ^[1]; Severs, J C; Wu, Q ^[2]

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1. Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology
2. Pacific Northwest National Lab., Richland, WA (United States). Environmental Molecular Science Lab.

Charge ladders of bovine carbonic anhydrase II, hen egg-white lysozyme, and bovine pancreatic trypsin inhibitor, prepared by partial acetylation of primary amino groups on the surface of the protein, have been analyzed by capillary electrophoresis (CE) and on-line electrospray ionization mass spectrometry (ESIMS) using solution conditions that maintain the native structure of the protein. CE was used to separate the proteins that constitute the charge ladder into individual rungs-protein derivatives that have the same number of acetylated amino groups and approximately the same net charge in solution. ESI was used to produce ions i the gas phase of the proteins that constitute each rung of the charge ladder; the mass spectra of these ions were obtained and analyzed. The distributions in charge states observed in the gas phase for the groups of proteins comprising each rung of the charge ladders were narrow, consistent with the retention of a compact structure of the proteins in the gas phase, and substantially independent of the number of acetylated amino groups. The ions observed in the gas phase had surface charge densities in a relatively narrow range of {approximately}0.9--1.5 units of charge per 10{sup 3}{angstrom}{sup 2} of surface area (as estimated from crystallographic structures). These results demonstrate that the distribution of charge states for proteins produced in the gas phase by ESI do not necessarily reflect the net charge of the protein in solution or the number of amino groups on the protein.

• Sponsoring Organization: USDOE, Washington, DC (United States); National Insts. of Health, Bethesda, MD (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 316055
• Journal Information: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 51 Vol. 102; ISSN 1089-5647; ISSN JPCBFK
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
CHARGE DENSITY
CHARGE STATES
CORRELATIONS
ELECTROPHORESIS
GASES
IONIZATION
MASS SPECTROSCOPY
PROTEINS
SOLUTIONS