112419-10-0Relevant articles and documents
Mechanistic insights into the bifunctional non-heme iron oxygenase carbapenem synthase by active site saturation mutagenesis
Phelan, Ryan M.,Townsend, Craig A.
supporting information, p. 7496 - 7502 (2013/07/11)
The carbapenem class of β-lactam antibiotics is known for its remarkable potency, antibacterial spectrum, and resistance to β-lactamase-mediated inactivation. While the biosynthesis of structurally complex carbapenems, such as thienamycin, share initial biochemical steps with carbapenem-3-carboxylate ( simple carbapenem), the requisite inversion at C5 and formation of the characteristic α,β-unsaturated carboxylate are different in origin between the two groups. Here, we consider carbapenem synthase, a mechanistically distinct bifunctional non-heme iron α-ketoglutarate-dependent enzyme responsible for the terminal reactions, C5 epimerization and desaturation, in simple carbapenem production. Interestingly, this enzyme accepts two stereoisomeric substrates and transforms each to a common active antibiotic. Owing both to enzyme and product instability, resorting to saturation mutagenesis of active site and selected second-sphere residues gave clearly differing profiles of CarC tolerance to structural modification. Guided by a crystal structure and the mutational data, in silico docking was used to suggest the positioning of each disastereomeric substrate in the active site. The two orientations relative to the reactive iron-oxo center are manifest in the two distinct reactions, C5-epimerization and C2/3-desaturation. These observations favor a two-step reaction scheme involving two complete oxidative cycles as opposed to a single catalytic cycle in which an active site tyrosine, Tyr67, after hydrogen donation to achieve bicyclic ring inversion, is further hypothesized to serve as a radical carrier.
Carboxymethylproline synthase catalysed syntheses of functionalised N-heterocycles
Hamed, Refaat B.,Mecinovic, Jasmin,Ducho, Christian,Claridge, Timothy D. W.,Schofield, Christopher J.
supporting information; experimental part, p. 1413 - 1415 (2010/06/12)
The utility of wild-type and variant carboxymethylproline synthases for biocatalysis was demonstrated by preparing functionalised 5-, 6- and 7-membered N-heterocycles from amino acid aldehydes and (alkylated) malonyl-coenzyme A derivatives; the N-heterocycles produced were converted to the corresponding bicyclic β-lactams by a carbapenem synthetase. The Royal Society of Chemistry 2010.
