Natural products that contain ortho-quinones show great potential as anticancer agents but have been largely discarded from clinical development because their redox-cycling behaviour results in general systemic toxicity. Here we report conjugation of ortho-quinones to a carrier, which simultaneously masks their underlying redox activity. C-benzylation at a quinone carbonyl forms a redox-inactive benzyl ketol. Upon a specific enzymatic trigger, an acid-promoted, self-immolative C–C bond-cleaving 1,6-elimination mechanism releases the redox-active hydroquinone inside cells. By using a 5-lipoxygenase modulator, β-lapachone, we created cathepsin-B-cleavable quinone prodrugs. We applied the strategy for intracellular release of β-lapachone upon antibody-mediated delivery. Conjugation of protected β-lapachone to Gem-IgG1 antibodies, which contain the variable region of gemtuzumab, results in homogeneous, systemically non-toxic and conditionally stable CD33+-specific antibody–drug conjugates with in vivo efficacy against a xenograft murine model of acute myeloid leukaemia. This protection strategy could allow the use of previously overlooked natural products as anticancer agents, thus extending the range of drugs available for next-generation targeted therapeutics.
Many bioconjugation strategies for DNAo ligonucleotides and antibodies suffer limitations,s uch as sitespecificity,s toichiometry and hydrolytic instability of the conjugates,w hichm akes them unsuitable for biological applications.H ere,w er eport an ew platform for the preparation of DNA-antibody bioconjugates with as imple benzoylacrylic acid pentafluorophenyl ester reagent. Benzoylacryliclabelled oligonucleotides prepared with this reagent can be sitespecifically conjugated to ar ange of proteins and antibodies through accessible cysteine residues.T he homogeneity of the prepared DNA-antibody bioconjugates was confirmed by an ew LC-MS protocol and the bioconjugate probes were used in fluorescence or super-resolution microscopyc ell imaging experiments.T his work demonstrates the versatility and robustness of our bioconjugation protocol that gives sitespecific,w ell-defined and plasma-stable DNA-antibody bioconjugates for biological applications.
Methods that allow for chemical site-selective dual protein modification are scarce. Here, we provide proof-of-concept for the orthogonality and compatibility of a method for regioselective lysine modification with strategies for protein modification at cysteine and genetically encoded ketone-tagged amino acids. This sequential, orthogonal approach was applied to albumin and a therapeutic antibody to create functional dual site-selectively labelled proteins.
Many bioconjugation strategies for DNAo ligonucleotides and antibodies suffer limitations,s uch as sitespecificity,s toichiometry and hydrolytic instability of the conjugates,w hichm akes them unsuitable for biological applications.H ere,w er eport an ew platform for the preparation of DNA-antibody bioconjugates with as imple benzoylacrylic acid pentafluorophenyl ester reagent. Benzoylacryliclabelled oligonucleotides prepared with this reagent can be sitespecifically conjugated to ar ange of proteins and antibodies through accessible cysteine residues.T he homogeneity of the prepared DNA-antibody bioconjugates was confirmed by an ew LC-MS protocol and the bioconjugate probes were used in fluorescence or super-resolution microscopyc ell imaging experiments.T his work demonstrates the versatility and robustness of our bioconjugation protocol that gives sitespecific,w ell-defined and plasma-stable DNA-antibody bioconjugates for biological applications.
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