Xanthones are natural products present in plants and microorganisms. In plants, their biosynthesis starts with regioselective cyclization of 2,3′,4,6-tetrahydroxybenzophenone to either 1,3,5- or 1,3,7-trihydroxyxanthones, catalysed by cytochrome P450 (CYP) enzymes. Here we isolate and express CYP81AA-coding sequences fromHypericum calycinumandH. perforatumin yeast. Microsomes catalyse two consecutive reactions, that is, 3′-hydroxylation of 2,4,6-trihydroxybenzophenone and C–O phenol coupling of the resulting 2,3′,4,6-tetrahydroxybenzophenone. Relative to the inserted 3′-hydroxyl, the orthologues Hc/HpCYP81AA1 cyclize via theparaposition to form 1,3,7-trihydroxyxanthone, whereas the paralogue HpCYP81AA2 directs cyclization to theorthoposition, yielding the isomeric 1,3,5-trihydroxyxanthone. Homology modelling and reciprocal mutagenesis reveal the impact of S375, L378 and A483 on controlling the regioselectivity of HpCYP81AA2, which is converted into HpCYP81AA1 by sextuple mutation. However, the reciprocal mutations in HpCYP81AA1 barely affect its regiospecificity. Product docking rationalizes the alternative C–O phenol coupling reactions. Our results help understand the machinery of bifunctional CYPs.

Wound infections originate when exogenous or endogenous bacterial pathogens can circumvent the barrier of the wound dressing and invade the wound bed. Bacterial colonization causes inflammation, stalls the healing process, and carries the risk of dissemination to other tissues. In addition, current antimicrobial dressings fail to resolve an infection once it has been established because debris of the killed bacteria rapidly accumulates on their surface and hampers the antimicrobial action. Faced with this challenge, hybrid synthetic‐natural water‐soluble macromolecules are designed that self‐assemble onto the surface of dressings to generate an antifouling brush functionalized with endolysin, a bactericidal enzyme that poses no harm for eukaryotic cells. The simultaneous action of the brush and the enzyme not only prevents the colonization of the dressing, but also enables the coating to kill planktonic bacteria with even higher efficiency than the free enzyme. Remarkably, the Kill&Repel coating could completely eradicate bacteria in a simulated infection without allowing the adhesion of residues on the surface. Thus, this strategy opens a revolutionary approach for protecting and treating an infected wound in a safer and more efficient manner.

Enzymes are nature's catalysts and have great potential for sustainable processes from renewable resources. The adaptation of enzymes to the requirements of industrial processes is a prerequisite to harness their benefits in large-scale transformations for the synthesis of fine chemicals, food products, and pharmaceuticals. Immobilisation of wild-type or engineered enzymes using natural and synthetic carriers has been extensively employed to improve catalytic performance, ensure recovery and reuse, and thereby promote their use in industrial processes. Over the past three decades, significant progress has been achieved in the design and application of immobilised enzymes. Microgels as containers for protein immobilisation are advancing into a promising alternative as reflected by a growing body of literature that documents their use in sustainable catalytic processes. Microgels are crosslinked submicron-sized colloidal polymer networks and in this review, we summarise the progress in the synthesis and applications of enzyme-loaded microgels (μ-Gelzymes). We start by exploring the different approaches used for enzyme immobilisation on or within microgels and give representative examples for the use of μ-Gelzymes in different applications. Subsequently, the potential of μ-Gelzymes in achieving sustainable catalysis is discussed from a green chemistry perspective. Finally, we draw future directions for further improvement of biocatalytic μ-Gelzymes as an emerging interdisciplinary research field of interactive soft matter.

In plants, prenylation of metabolites is widely distributed to generate compounds with efficient defense potential and distinct pharmacological activities profitable to human health. Prenylated compounds are formed by members of the prenyltransferase (PT) superfamily, which catalyze the addition of prenyl moieties to a variety of acceptor molecules. Cell cultures of Hypericum calycinum respond to elicitor treatment with the accumulation of the prenylated xanthone hyperxanthone E. A cDNA encoding a membrane-bound PT (HcPT) was isolated from a subtracted cDNA library and transcript preparations of H. calycinum. An increase in the HcPT transcript level preceded hyperxanthone E accumulation in cell cultures of H. calycinum treated with elicitor. The HcPT cDNA was functionally characterized by expression in baculovirus-infected insect cells. The recombinant enzyme catalyzed biosynthesis of 1,3,6,7-tetrahydroxy-8-prenylxanthone through regiospecific C–8 prenylation of 1,3,6,7-tetrahydroxyxanthone, indicating its involvement in hyperxanthone E formation. The enzymatic product shared significant structural features with the previously reported cholinesterase inhibitor γ-mangostin. Thus, our findings may offer a chance for semisynthesis of new active agents to be involved in the treatment of Alzheimer’s disease.