Terpene cyclization reactions are fascinating owing to the precise control of connectivity and stereochemistry during the catalytic process. Cyclooctat-9-en-7-ol synthase (CotB2) synthesizes an unusual 5-8-5 fused-ring structure with six chiral centers from the universal diterpene precursor, the achiral C₂₀ geranylgeranyl diphosphate substrate. An unusual new mechanism for the exquisite CotB2-catalyzed cyclization that involves a carbon–carbon backbone rearrangement and three long-range hydride shifts is proposed, based on a powerful combination of in vivo studies using uniformly ¹³C-labeled glucose and in vitro reactions of regiospecifically deuterium-substituted geranylgeranyl diphosphate substrates. This study shows that CotB2 elegantly demonstrates the synthetic virtuosity and stereochemical control that evolution has conferred on terpene synthases.

Terpene cyclization reactions are fascinating owing to the precise control of connectivity and stereochemistry during the catalytic process. Cyclooctat-9-en-7-ol synthase (CotB2) synthesizes an unusual 5-8-5 fused-ring structure with six chiral centers from the universal diterpene precursor, the achiral C₂₀ geranylgeranyl diphosphate substrate. An unusual new mechanism for the exquisite CotB2-catalyzed cyclization that involves a carbon–carbon backbone rearrangement and three long-range hydride shifts is proposed, based on a powerful combination of in vivo studies using uniformly ¹³C-labeled glucose and in vitro reactions of regiospecifically deuterium-substituted geranylgeranyl diphosphate substrates. This study shows that CotB2 elegantly demonstrates the synthetic virtuosity and stereochemical control that evolution has conferred on terpene synthases.

Two new acyloin compounds were isolated from the thermophilic bacterium Thermosporothrix hazakensis SK20-1^T. Genome sequencing of the bacterium and biochemical studies identified the thiamine diphosphate (TPP)-dependent enzyme Thzk0150, which is involved in the formation of acyloin. Through extensive analysis of the Thzk0150-catalyzed reaction products, we propose a putative reaction mechanism involving two substrates: 4-methyl-2-oxovalerate as an acyl donor and phenyl pyruvate as an acyl acceptor.

Cyclolavandulyl diphosphate synthase (CLDS; estimated molecular weight 23.1 kDa) from the soil bacterium Streptomyces sp. CL190 is an enzyme that catalyzes both the condensation of two molecules of C₅ dimethylallyl diphosphate (DMAPP) and the subsequent cyclization. CLDS was crystallized in the absence and the presence of the substrate DMAPP. Diffraction data were collected at a synchrotron source and the crystals diffracted to 2.00 and 1.73 Å resolution, respectively. The crystal obtained in the absence of DMAPP belonged to space group P2₁2₁2₁, with unit-cell parameters a = 39.0, b = 87.5, c = 113.6 Å. The crystal obtained in the presence of DMAPP belonged to space group P1, with unit-cell parameters a = 46.9, b = 61.7, c = 82.2 Å, α = 74.0, β = 84.5, γ = 86.0°.