J. Biol. Chem., Vol. 265, Issue 35, 21727-21732, 12, 1990
Characterization of affinity-purified juvenile hormone esterase from the plasma of the tobacco hornworm, Manduca sexta
K Venkatesh, YA Abdel-Aal, FB Armstrong and RM Roe
Department of Entomology, North Carolina State University, Raleigh 27695.
Juvenile hormone (JH) esterase found primarily in the hemolymph and tissues
of insects is a low abundance protein involved in the ester hydrolysis of
insect juvenile hormones, JHs. The enzyme was purified from the larval
plasma of wild-type Manduca sexta using an affinity column prepared by
binding the ligand, 3-[(4'-mercapto)butylthio]-1,1,1- trifluoropropan-2-one
(MBTFP), to epoxy-activated Sepharose. The purification was greater than
700-fold with a 72% recovery, and the purified enzyme appeared as a single
protein on sodium dodecyl sulfate- polyacrylamide gel electrophoresis,
immunoelectrophoresis, reverse phase high performance liquid
chromatography, and amino acid sequence analysis. The molecular weight was
66,000. The plasma JH esterase in wild-type, black, and white strains of M.
sexta was similar when analyzed by immunotitration, wide range (pH 3.5-9.0)
isoelectric focusing, and inhibition with MBTFP and 3-octylthio-1,1,1-
trifluoropropan-2-one (OTFP). Inhibition studies revealed a sensitive and
insensitive form (I50 = 10(-9) and 10(-6) M, respectively) in these three
biotypes. Narrow range isoelectric focusing (pH 4.0-7.0) indicated the
presence of two major isoelectric forms with pI values of 6.0 and 5.5, but
their inhibition kinetics with OTFP and O,O- diisopropyl
phosphorofluoridate were identical.