Active site mutagenesis of the putative Diels-Alderase macrophomate synthase
Although the macrophomate synthase active site is rich in potential functional groups, site-directed mutagenesis shows that only three residues are absolutely required for catalysis of oxaloacetate decarboxylation and trapping of the resulting enolate wit
Serafimov, Joerg M.,Lehmann, Hans Christian,Oikawa, Hideaki,Hilvert, Donald
Substrate Diversity of Macrophomate Synthase Catalyzing an Unusual Multistep Transformation from 2-Pyrones to Benzoates
Macrophomale synthase, which we have recently purified, catalyzes an unusual multistep transformation from 5-acetyl-4-methoxy-6-methyl-2-pyrone to 4-acetyl-3-methoxy-5-methyl-benzoic acid (macrophomic acid). To investigate the substrate diversity of the enzyme, 40 analogs of 2-pyrone were prepared and their relative efficiency was examined in the enzymatic conversions. The experimental results reveal the structural requirements of the substrates and the rough size of the enzyme active site, and eliminate the ambiguity caused by contamination by other enzymes in the whole-cell experiments.
Macrophomate synthase: Unusual enzyme catalyzing multiple reactions from pyrones to benzoates
Macrophomate synthase which catalyzes unusual multiple reactions from 2-pyrone (3) to macrophomic acid (1) has been purified in a homogenous state. The macrophomate synthase is a dimeric enzyme which requires Mg2+ as a co-factor and whose molec
Studies on Metabolites of Macrophoma commelinae. IV. Substrate Specificity in the Biotransformation of 2-Pyrones to Substituted Benzoic Acids
Substrate specificity in the novel biotransformation from 2-pyrone derivatives to substituted benzoic acids by Macrophoma commelinae (IFO 9570) was investigated by means of feeding experiments with various compounds.Among them, 2-pyrone derivatives substituted by an electron-donating group at C-4, by an electron-withdrawing group at C-5 and by an alkyl group at C-6 were converted to the corresponding benzoic acid derivatives in fairly good yields.The C3-unit precursors and intermediates were examined in stationary or shaking culture.Based on the experimental results obtained, a mechanism for this unique reaction is proposed. macrophoma commelinae IFO 9570; fungi; 2-pyrone; substituted benzoic acid; biotransformation; substrate specificity; aromatic ring formation; macrophomic acid
NOVEL BIOTRANSFORMATION OF A 2-PYRONE TO A SUBSTITUTED BENZOIC ACID
It was found that Macrophoma commelinae (IFO 9570) has an ability to transform 5-acetyl-4-methoxy-6-methyl-2-pyrone (1) to 4-acetyl-3-methoxy-5-methylbenzoic acid (2).This biotransformation was investigated using 13C- and 14C-labeled compounds.It is likely that 2 is formed by condensation of the added 2-pyrone and a catabolic pyruvate.KEYWORDS-Macrophoma commelinae; fungus; 2-pyrone; substituted benzoic acid; pyruvate; aromic ring formation