Page 29 - Tyrosine-Based Bioconjugations - Jorick Bruins
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complementary strand of DNA was introduced (Scheme 8, bottom), which was linked in an identical fashion to the N-terminal proline residue of fructose-bisphosphate aldolase (ALD). The enzyme was proven to retain its activity after immobilization and could be removed by adding a complementary DNA-strand, regenerating the DNA-bearing glass surface. Finally, fresh enzyme- bearing DNA could be added, and catalytic activity was achieved once more.
Scheme 8. Glass surfaces bearing aniline residues and their subsequent modification for DNA-directed immobilization. ALD = fructose-bisphosphate aldolase.
1.3.4. Quinone methides
Ortho-quinone methides (from now on referred to as quinone methides) are carbon analogues of regular quinones, with one of the oxygen atoms replaced by a carbon atom (most typically a methylene group). Quinone methide derivatives are widely reported in synthesis and catalysis,114-118 and, by virtue of their DNA alkylation properties,119, 120 are known as potent anticancer drugs.
Like quinones, quinone methides have both an electrophilic character and a propensity to undergo (4+2) cycloaddition.117, 118 In this regard, it is clear that protein modification based on quinone methides requires careful modulation of stability and reactivity. To this end, Rokita et al. explored the effects of substituents on the formation and stability of quinone methide derivatives and their adducts based on nucleophilic addition.121, 122 Recently, Bieniarz et al. reported covalent labeling of tissue in close proximity of cancer epitopes with in situ generated
General Introduction
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