Purification of Escherichia coli Heat-Stable Enterotoxin

Richard N. Greenberg, Abdul M.K. Saeed

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


The chapter describes the purification of enterotoxigenic Escherichia coli (ETEC) enterotoxin STa, which is the heat-stable mouse-active enterotoxin. ETEC may induce clinically significant intestinal fluid secretion (i.e., diarrhea) in humans and animals by production of enterotoxins. Several types of ETEC enterotoxins are recognized, each with a unique structure and mechanism of action. STa activates particulate guanylate cyclase in intestinal epithelial cells. A modification suckling mouse assay (SMA) is used for detection and quantitation of STa throughout the purification steps. Sequence analysis of STa peptides is performed by the manual microsequencing technique of Chang using the double-coupling method with dimethylaminoazobenze isothiocyanate/phenyl isothiocyanate. After each cycle of derivatization, the labeled amino-terminal amino acid is cleaved. For preparative purposes the described scheme can be scaled upward to produce larger amounts of STa. The derivatized amino acids are identified by their retention times in comparison with amino acid standards derivatized and chromatographed under the same conditions.

Original languageEnglish
Pages (from-to)126-137
Number of pages12
JournalMethods in Enzymology
Issue numberC
StatePublished - Jan 1988

Bibliographical note

Funding Information:
This work was supported by a Medical Research Council (UK) Grant Number G8306837SB. I thank Dr. R. Parton for his advice.

Funding Information:
The work was supported in part by research funds from the Institute for Medical Education and Research, Saint Louis, Missouri. We thank Dr. Donald Kennedy for encouragement and support, Dr. Nancy S. Magnuson for helpful suggestions, and Mrs. Sue Stevens for excellent secretarial assistance.

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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