Thebaine is Selectively Demethylated by Thebaine 6--Demethylase and Codeine-3--demethylase at Distinct Binding Sites: A Computational Study.

Two homologous 2-oxoglutarate-dependent (ODD) nonheme enzymes thebaine 6--demethylase (T6ODM) and codeine-3--demethylase (CODM), are involved in the morphine biosynthesis pathway from thebaine, catalyzing the -demethylation reaction with precise regioselectivity at C6 and C3 positions of thebaine respectively. We investigated the origin of the regioselectivity of these enzymes by combined molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) calculations and found that Thebaine binds at the two distinct sites of T6ODM and CODM, which determines the regioselectivity of the enzymes. A remarkable oxo rotation is observed in the decarboxylation process.

Regio- and stereoselectivity in the CYP450-catalyzed hydroxylation of complex terpenoids: a QM/MM study.

The site-selective C-H oxidation of terpenoids by P450 attracts great attention because of their wide range of biological activities. However, the binding and catalytic mechanism of P450 for the hydroxylation of complex terpenoid substrates remains elusive, which has limited the rational engineering of P450 as a biocatalyst for terpenoid biosynthesis. Here, we studied the origin of the selectivity and reactivity of P450BM3 in the hydroxylation of terpenoids by combining molecular dynamics simulations and QM/MM calculations, using artemisinin as a model compound.

The mutagenesis of a single site for enhancing or reversing the enantio- or regiopreference of cyclohexanone monooxygenases.

The mutagenesis of a "second sphere" switch residue of CHMO could control its enantio- and regiopreference. Replacing phenylalanine (F) at position 277 of CHMO into larger tryptophan (W) enabled a significant enhancement of enantio- or regioselectivity toward structurally diverse substrates, moreover, a complete reversal of enantio- or regiopreference was realized by mutating F277 into a range of smaller amino acids (A/C/D/E/G/H/I/K/L/M/N/P/Q/R/S/T/V).

The phosphorylation mechanism of mevalonate diphosphate decarboxylase: a QM/MM study.

Mevalonate diphosphate decarboxylase (MDD) catalyses a crucial step of the mevalonate pathway via Mg2+-ATP-dependent phosphorylation and decarboxylation reactions to ultimately produce isopentenyl diphosphate, the precursor of isoprenoids, which is essential to bacterial functions and provides ideal building blocks for the biosynthesis of isopentenols. However, the metal ion(s) in MDD has not been unambiguously resolved, which limits the understanding of the catalytic mechanism and the exploitation of enzymes for the development of antibacterial therapies or the mevalonate metabolic pathway for the biosynthesis of biofuels. Here by analogizing structurally related kinases and molecular dynamics simulations, we constructed a model of the MDD-substrate-ATP-Mg2+ complex and proposed that MDD requires two Mg2+ ions for maintaining a catalytically active conformation.

Laccase-immobilized tannic acid-mediated surface modification of halloysite nanotubes for efficient bisphenol-A degradation.

Halloysite nanotubes (HNTs) have been pursued as promising carriers for enzyme immobilization, but the lack of functional groups severely limits their applications. Herein, we reported a simple tannic acid (TA)-mediated surface modification strategy for the fabrication of HNT-based efficient enzyme immobilization supports. Particularly, TA was first self-polymerized and deposited onto the surface of HNTs to form a thin active film a mussel-inspired method, and the model enzyme laccase was directly conjugated the Michael addition and/or Schiff base condensation between quinone groups on poly(tannic acid) layer surfaces and exposed amine groups on laccase surfaces.