Identification and Characterization of the Glucosinolate-Myrosinase System in Caper (Capparis ovata Desf.)

WOS: 000270780900013Myrosinase (EC 3.2.1.147) catalyzes cleavage of glucosinolates, which consist of a thioglucoside moiety linked to amino acid-derived side chains. Myrosinase activity and expression profiles were investigated together with glucosinolate contents in Capparis ovata (caper) in order to characterize the glucosinolate-myrosinase system. The desulfoglucosinolates-glucocapparin, glucoiberin, progoitrin, epiprogoitrin, sinigrin, gluconapin, glucosinalbin, and glucobrassicin-were extracted and quantified from leaves, seeds, flowers, flower buds, and young shoots. The major desulfoglucosinolate was glucocapparin, which accumulated to values of 39.35 +/- 0.09 and 25.56 +/- 0.11 mu mol g(-1) dry weight in seed and leaf extracts, respectively. Myrosinase has high activity in caper seeds, leaves, flowers, and flower bud tissues having the highest total activities in seed extracts (79.23 +/- 0.18 U). However, specific activities were the highest in flower bud extracts (200.44 +/- 0.09 U mg(-1) protein). The myrosinase protein migrated as a single band with a molecular weight of 65 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis and on Western blots probed with the myrosinase-specific 3D7 antibodies. Native gel electrophoresis revealed two putative myrosinase isoenzymes in seeds, leaves, and flower tissues. The caper homolog of the Arabidopsis thaliana TGG1 gene was differentially expressed in seeds, leaves, flowers, and flower buds with the highest expression levels in leaves and flower bud tissues.Scientific and Technical Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [2435-104T044]; Ege University Research FoundationEge University [2005-BIL-012]The authors wish to thank Prof. Christine Foyer for her critical reading and helpful contributions to the manuscript, Prof. Johan Meijer for kindly providing the lyophilized 3D7 monoclonal hybridoma and for his helpful advices, and Dr. Richard N. Bennett for kindly providing the glucosinolate standards. This research was funded by grants TBAG 2435-104T044 from The Scientific and Technical Research Council of Turkey (TUBITAK) and 2005-BIL-012 from Ege University Research Foundation