Vermunt AMW, Vermeesch AMG, de Kort CAD (1997): Purification and characterization of juvenile hormone esterase hemolymph of the Colorado potato beetle. Arch Insect Biochem Physiol 35:261-277.

Abstract

The last sentence in the abstract was printed incorrectly. The correct sentence is printed below in the abstract. The authors regret the error. In the Colorado potato beetle (Leptinotarsa decemlineata), low juvenile hormone (JH) titers are necessary to initiate metamorphosis and diapause. Low JH titers coincide with high activities of JH esterase, which occur mainly in the hemolymph. The specific activity of JH esterase appeared to be highest in the last larval instar, at day 3 after the moult, and reached a value of 13.5 nmol/min/mg. JH esterase was purified from hemolymph collected at this stage by a sequence of separation systems including preparative nondenaturing PAGE, isoelectric focusing and SDS-PAGE. The enzyme was demonstrated to have a molecular weight of 120,000 and was composed of two subunits with molecular weight of 57,000, which were not linked by disulphide bridges. Isoelectric focusing revealed two forms of the enzyme with isoelectric points of 5.5 and 5.6. The Km and kcat of the purified enzyme were determined. The major form with pI 5.6 had a Km of 1.4 × 10–6M and a kcat of 0.9 s–1 and the minor form with pI 5.5 had a Km of 2.2 × 10–6M and a kcat 1.9 s–1. The quaternary structure of L. Decemlineata JH esterase as a dimer, differs from JH esterases in other species, which are monomers.