Biochemical and structural characterization of a novel -isoleucine-4-dioxygenase (RaIDO) from Rahnella aquatilis.

The -isoleucine-4-dioxygenase converts -isoleucine (Ile) into(2S,3R,4S)-4-(OH)-isoleucine (4-HIL), a naturally occurring hydroxyl amino acid, which is a promising compound for drug and functional food development. Here, a novel -isoleucine-4-dioxygenase (RaIDO) from Rahnella aquatilis was cloned, expressed and characterized, as one of only a few reported -isoleucine-4-dioxygenases. RaIDO showed high catalytic efficiency with Ile as the substrate, as well as good stability.

[Enzymatic properties and degradation characterization of a bis(2-hydroxyethyl) terephthalate hydrolase from sp].

The discovery of new enzymes for poly(ethylene terephthalate) (PET) degradation has been a hot topic of research globally. Bis-(2-hydroxyethyl) terephthalate (BHET) is an intermediate compound in the degradation of PET and competes with PET for the substrate binding site of the PET-degrading enzyme, thereby inhibiting further degradation of PET. Discovery of new BHET degradation enzymes may contribute to improving the degradation efficiency of PET.

Switchable enzyme mimics based on self-assembled peptides for polyethylene terephthalate degradation.

Polyethylene terephthalate (PET), the most abundant polyester plastic, has become a global concern due to its refractoriness and accumulation in the environment. In this study, inspired by the structure and catalytic mechanism of the native enzyme, peptides, based on supramolecular self-assembly, were developed to construct enzyme mimics for PET degradation, which were achieved by combining the enzymatic active sites of serine, histidine and aspartate with the self-assembling polypeptide MAX. The two designed peptides with differences in hydrophobic residues at two positions exhibited a conformational transition from random coil to β-sheet by changing the pH and temperature, and the catalytic activity followed the self-assembly "switch" with the fibrils formed β-sheet, which could catalyze PET efficiently.