| Summary: | The development of artificial metalloenzymes is an expanding field, involving various protein scaffolds and incorporating a wide range of transition-metal catalysts. Due to its pH-dependent disassembling properties, apoferritin has been used extensively for various purposes. However, very few studies reported its use as a scaffold for the design of artificial metalloenzymes.
This study investigated the development of an apoferritin-based artificial metalloenzyme, based on covalent conjugation with a manganese-salen complex, applied to the catalysis of sulphide oxidation.
A mouse recombinant heavy-chain apoferritin mutant, containing a unique and reactive cysteine, in position 68, pointing towards its hollow core, was expressed and purified. A manganese-salen bearing a maleimide linker was synthesised and covalently linked to apoferritin’s cysteine 68, via a Michael addition reaction.
The catalytic activity towards the enantioselective oxidation of thioanisole was assessed in both organic and aqueous media and has resulted in pH-dependent activity and enantioselectivity, with up to 69 % conversion and 17 % ee, due to the reassembling of the conjugated apoferritin nanocapsule.
However, background reactions exhibited high yields in certain conditions and the stability of the apoferritin-based artificial metalloenzyme was extremely relative at pH ranges where native apoferritin was supposed to be stable. Therefore, further research is recommended to improve three key features of this catalyst: stability, enantioselectivity and reactivity.
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