Single-chain antibody; fragments (scAb), specific fur the chlorophenoxy aci
d herbicide mecoprop, have been expressed and purified from the bacterium E
scherichia coli. Co-expression with the colE1-compatible, arabinose-inducib
le, skp expression vector pHELP1 prevented bacterial lysis and significantl
y increased both total and functional expression yield. The periplasmic pro
tein, SKP, may have a role as a generic detoxification protein. Surface pla
smon resonance (BIAcore 2000) analysis confirmed that the purified scAb ret
ained similar binding kinetics to the monoclonal antibody (Mab) front which
it was cloned. In competition ELISA, the bacterial scAb showed the same sp
ecificity for mecoprop and a related herbicide, MCPA, as the Mab but an inc
rease in sensitivity for free antigen in all ELISA. formats.
Bacterially expressed antibody fragments provide a simple, sensitive and co
st-effective alternative to the traditional production of diagnostic Mabs v
ia tissue culture.