Cyclic enterobacterial common antigen: potential contaminant of bacterially expressed protein preparations.
We have previously reported the identification of the cyclic enterobacterial common antigen (ECA(CYC)) polysaccharide in E. coli strains commonly used for heterologous protein expression (PJA Erbel et al., J. Bacteriol. 185 (2003): 1995). Following this initial report, interactions among several NMR groups established that characteristic N -acetyl signals of ECA(CYC) have been observed in (15)N-(1)H HSQC spectra of samples of various bacterially-expressed proteins suggesting that this water-soluble carbohydrate is a common contaminant. We provide NMR spectroscopic tools to recognize ECA(CYC) in protein samples, as well as several methods to remove this contaminant. Early recognition of ECA-based NMR signals will prevent time-consuming analyses of this copurifying carbohydrate.
Erbel
Paul J A
PJ
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas TX 75390-9038, USA.
Seidel
Ronald
R
Macintosh
Scott E
SE
Gentile
Lisa N
LN
Amor
Juan C
JC
Kahn
Richard A
RA
Prestegard
James H
JH
McIntosh
Lawrence P
LP
Gardner
Kevin H
KH
D000942:Antigens, Bacterial / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011135:Polysaccharides, Bacterial / Q000737:chemistry*
D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial; C017286:enterobacterial common antigen