Site-specific PEGylation of lidamycin and its antitumor activity

In this study,N-terminal site-specific mono-PEGylation of the recombinant lidamycin apoprotein(r LDP) of lidamycin(LDM) was prepared using a polyethyleneglycol(PEG) derivative(Mw20 k Da) through a reactive terminal aldehyde group under weak acidic conditions(p H 5.5).The biochemical properties of m PEG-r LDP-AE,an enediyne-integrated conjugate,were analyzed by SDSPAGE,RP-HPLC,SEC-HPLC and MALDI-TOF.Meanwhile,in vitro and in vivo antitumor activity of m PEG-r LDP-AE was evaluated by MTT assays and in xenograft model.The results indicated that m PEGr LDP-AE showed significant antitumor activity both in vitro and in vivo.After PEGylation,m PEG-r LDP still retained the binding capability to the enediyne AE and presented the physicochemical characteristics similar to that of native LDP.It is of interest that the PEGylation did not diminish the antitumor efficacy of LDM,implying the possibility that this derivative may function as a payload to deliver novel tumortargeted drugs.