Biosynthesis of corrins. A cell-free system from Propionibacterium shermanii

Complexity reduction and opportunities in the design, integration and intensification of biocatalytic processes for metabolite synthesis

The biosynthesis of metabolites from available starting materials is becoming an ever important area due to the increasing demands within the life science research area. Access to metabolites is making essential contributions to analytical, diagnostic, therapeutic and different industrial applications. These molecules can be synthesized by the enzymes of biological systems under sustainable process conditions. The facile synthetic access to the metabolite and metabolite-like molecular space is of fundamental importance. The increasing knowledge within molecular biology, enzyme discovery and production together with their biochemical and structural properties offers excellent opportunities for using modular cell-free biocatalytic systems. This reduces the complexity of synthesizing metabolites using biological whole-cell approaches or by classical chemical synthesis. A systems biocatalysis approach can provide a wealth of optimized enzymes for the biosynthesis of already identified and new metabolite molecules.

Discovering nature's diverse pathways to vitamin B12: a 35-year odyssey

The chronology of the discoveries along the pathway of vitamin B(12) biosynthesis is reviewed from a personal perspective, including discussion of the most recent finding that two pathways to B(12) exist-one aerobic and one anaerobic-which differ mainly in the ring contraction mechanisms that convert porphyrin to corrin.

Reflections on the discovery of nature's pathways to vitamin B12

The chronology of the discoveries along the pathway of vitamin B12 biosynthesis is reviewed from a personal perspective, including discussion of the most recent finding that two pathways to B12 exist--one aerobic and one anaerobic--which differ mainly in the ring contraction mechanisms which convert porphyrin to corrin.

Biosynthesis of natural products

The experimental verification of a proposed biosynthetic pathway for a given natural product is often difficult to obtain with the use of the whole organism (permeability factors) or, in the case of higher plants, a cell-free system. Until the purified enzyme for each step of biosynthesis is available, biosynthetic studies can, however, be carried out, albeit with modest incorporation values, by means of either hydroponic or injection methodology. Where viable seed sources are available it is suggested that improvements of several orders of magnitude in incorporation can be achieved by a short-term incubation (small pool size of precursors; trapping of reactive intermediates) or a long-term feeding (equilibration of precursor with the compartmentalized or induced synthetases). In bacterial, fungal, mammalian, and plant systems, where incorporation efficiencies provide the opportunity to study (13)C enrichment (at least equal to natural abundance of the isotope), we can expect a rapid expansion since the method removes the tedium of carbon-by-carbon degradation. For the next few years, however, the prognosis would seem to favor parallel studies of (13)C and (2)H, and of (14)C/(3)H ratio techniques since the last-mentioned method provides more information concerning the stereoselectivity of labeling processes on the microgram scale.