Premium
Characterisation of aphid myrosinase and degradation studies of glucosinolates
Author(s) -
Francis Frédéric,
Lognay Georges,
Wathelet JeanPaul,
Haubruge Eric
Publication year - 2002
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.10042
Subject(s) - myrosinase , glucosinolate , brevicoryne brassicae , biology , fast protein liquid chromatography , aphid , chromatography , size exclusion chromatography , biochemistry , ammonium sulfate precipitation , aphididae , botany , chemistry , enzyme , homoptera , pest analysis , brassica
Myrosinase from Brevicoryne brassicae was purified by ammonium sulfate fractionation, dialysis, and chromatography on a DEAE column. The chromatography yielded a single peak and a 115.6‐fold purification. Further FPLC gel filtration gave a single peak at 120 kDa. Denaturing SDS/PAGE of the protein revealed a single band at 60 kDa, indicating that the native B. brassicae myrosinase is a dimer. Kinetic parameters towards 8 glucosinolates were calculated. Strong differences of V max and K m were observed depending on the substrate. Degradation products of each glucosinolate were identified and quantified by GC‐MS and GLC‐FID, respectively. Using both crude aphid homogenates and purified myrosinase, two unique hydroxyglucosinolates, 3‐butenyl‐ and benzyl‐isothiocyanates were identified from progoitrin ((2S)‐2‐hydroxybut‐3‐enyl‐glucosinolate) and sinalbin (4‐hydroxybenzyl‐glucosinolate) degradation respectively. Addition of ascorbic acid to the reaction mixtures containing sinalbin and progoitrin caused the production of hydroxylated degradation products usually associated with plant myrosinase metabolisation. The occurrence of the myrosinase system in B. brassicae is discussed in terms of similar allelochemical adaptation between the herbivore and its host plant. Arch. Insect Biochem. Physiol. 50:173–182, 2002. © 2002 Wiley‐Liss, Inc.