リジン付加反応を利用したイソチオ シアネート類の標的分子探索のため の基礎的研究

　Isothiocyanates (ITCs) are contained as glucosinolates in cruciferous plants such as Wasabia japonica ( wasabi) and broccoli. Numerous studies have shown that ITCs have beneficial effects in our body such as induction of detoxification enzymes and inhibitory effects on cancer cell growth. The biological activities of ITCs are considered to be triggered in the reaction of ITC with thiols to form an unstable thiocarbamoyl adduct. On the other hand, ITCs are also known to react with amino moieties stably under alkaline pH. However, the reaction of ITCs with amino moieties under physiological conditions has not been explored fully. Therefore, we investigated the reactivity of allyl ITC (AITC) with amino groups under neutral conditions. When AITC was incubated with bovine serum albumin (BSA) as a model protein in a phosphate buffer (pH 7.4), amino groups were decreased. In addition, AITCmodified Nα‒benzoyl-glycyl-L-lysine (BGK) with a Nε‒thiocarbamoyl linkage was detected by incubation of AITC and BGK in the buffer. To verify the transformation of ITC from predominant target ‘thiol’ to amine, synthetic AITC‒modified Nα‒acetyl-L-cysteine (NAC) was incubated with BGK. The AITC‒Lys adduct was generated in a timedependent manner, while AITC‒NAC adduct was degraded. Furthermore, AITC‒Lys adduct was detected from the mixture of AITC‒NAC and BSA using a novel anti‒AITC‒Lys monoclonal antibody. Thus, the adduct of ITC and Lys residue may be a useful tag for identification of ITC target molecules.

研究紹介 (Research Report)