Fig 1. Glucosinolate breakdown pathways.

Pathways are illustrated using allylglucosinolate as an example. Myrosinase-catalyzed glucosinolate hydrolysis yields an unstable aglucone that undergoes a spontaneous Lossen-like rearrangement to the isothiocyanate. In the presence of specifier proteins, alternative breakdown products (simple nitrile, epithionitrile, thiocyanate) are formed. Boxes indicate hypothetic mechanisms supposively mediated by specifier proteins. Specifier proteins analyzed in the present study are assigned to the boxes. If the aglucone lacks the structural requirements for epithionitrile and/or thiocyanate formation, all types of specifier proteins promote simple nitrile formation (not shown). For more detailed explanations, see text. Boxed reaction schemes are redrawn from [20] and [21] with modifications.