Binding and degradation of juvenile hormone III by haemolymph proteins of the Colorado potato beetle: a re-examination

• Main Authors: Kort, C. A. D. de, Peter, Martin G., Koopmanschap, A. B.
• Format: Others
• Language: English
• Published: Universität Potsdam 1983
• Subjects: Juvenile hormone; Leptinotarsa decemlineata; JH-III-specific carrier protein; enantioselectivity; Life sciences
• Online Access: http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16777; http://opus.kobv.de/ubp/volltexte/2008/1677/

The haemolymph of the adult Colorado potato beetle, Lepinotarsa decemlineata Say, contains a high molecular weight (MW > 200,000) JH-III specific binding protein. The Kd value of the protein for racemic JH-III is 1.3 ± 0.2 × 10−7 M. It has a lower affinity for racemic JH-I and it does not bind JH-III-diol or JH-III-acid. The binding protein does discriminate between the enantiomers of synthetic, racemic JH-III as was determined by stereochemical anaysis of the bound and the free JH-III. Incubation of racemic JH-III with crude haemolymph results in preferential formation of (10S)-JH-III-acid, the unnatural configuration. The JH-esterase present in L. decemlineata haemolymph is not enantioselective. It is concluded that the most important function of the binding protein is that of a specific carrier, protecting the natural hormone against degradation by esterases. The carrier does not protect JH-I as efficiently as the lower homologue.