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ISSN
1672-9145
Acta Biochim Biophys Sin
2005, 37(2): 126–132
CN 31-1940/Q
LT(K63/R72), a New Mutant of Escherichia coli Heat-labile
Enterotoxin, Exhibits Characteristics More Similar to LT(K63) than LT(R72)
Qiang FENG1,2, Jun YANG1, Ping LUO1,
Wei-Jun ZHANG1, and Quan-Ming
ZOU1*
1Department
of Clinical Microbiology and Immunology, Third Military Medical University,
Chongqing 400038, China;
2Department
of Life Sciences and Chemistry, Chongqing Education College, Chongqing 400067,
China
Abstract LT(K63), a non-toxic mutant and LT(R72), a low toxic mutant of E.
coli heat-labile enterotoxin are frequently used mucosal adjuvants. In many
cases, the adjuvanticity of LT(K63) is lower than that of LT(R72), but LT(K63),
which induces a mixed Th1/Th2 response, exhibits a higher level of protection
than LT(R72) which induces a polarized Th2-type response. To utilize the
advantages of both adjuvants, a double-mutation LT(K63/R72) was generated and
purified. The characterization results showed that there was no significant
difference in production rate and immunogenicity between wild type LT and LT
mutants. The results also showed that the toxicity and the trypsin sensitivity
of LT(K63/R72) are between that of LT(K63) and LT(R72). Using HPLC, when
samples in an OHpak SB-800 column were eluted by denatural buffer (TEAN
containing 10 mg/ml SDS), we found the stability of LT(K63/R72) was higher than
that of LT(R72) and lower than that of LT(K63). Through further analyzes, we
found that LT(K63/R72) exhibits characteristics more closely related to LT(K63)
than LT(R72).
Key words Escherichia coli heat-labile
enterotoxin; mutants; LT(K63); LT(R72); LT(K63/R72)
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Received: November 1, 2004 Accepted: December 30,
2004
This work was supported by a grant from the National High Technology
Research and Development Program of China (No. 2001AA215161)
*Corresponding author: Tel/Fax, 86-23-68752316; E-mail, [email protected]