Receptor-Based Artificial Metalloenzymes on Living Human Cells

Artificial
metalloenzymes are known to be promising tools for biocatalysis,
but their recent compartmentalization has led to compatibly with cell
components thus shedding light on possible therapeutic applications.
We prepared and characterized artificial metalloenzymes based on the
A2A adenosine receptor embedded in the cytoplasmic membranes
of living human cells. The wild type receptor was chemically engineered
into metalloenzymes by its association with strong antagonists that
were covalently bound to copper­(II) catalysts. The resulting cells
enantioselectively catalyzed the abiotic Diels–Alder cycloaddition
reaction of cyclopentadiene and azachalcone. The prospects of this
strategy lie in the organ-confined in vivo preparation of receptor-based
artificial metalloenzymes for the catalysis of reactions exogenous
to the human metabolism. These could be used for the targeted synthesis
of either drugs or deficient metabolites and for the activation of
prodrugs, leading to therapeutic tools with unforeseen applications.

人工金属酶（artificial metalloenzymes）素来被视为生物催化领域极具潜力的工具，而近期其区室化研究进展使其能够与细胞组分兼容，由此为其潜在治疗应用开辟了新方向。本研究以嵌入活人体细胞质膜的A2A腺苷受体（A2A adenosine receptor）为基础，制备并表征了人工金属酶：通过将野生型受体与共价结合铜(II)催化剂的强效拮抗剂相结合，将其化学改造为金属酶。所得工程化细胞可对环戊二烯与氮杂查尔酮的非生物狄尔斯–阿尔德（Diels–Alder）环加成反应实现对映选择性催化。该策略的前景在于，可在器官限定的体内环境中制备基于受体的人工金属酶，用于催化人体代谢以外的外源性反应。此类酶可用于靶向合成药物或体内缺乏的代谢物，以及激活前体药物，由此开发出具备未知应用潜力的治疗工具。