Patulin biosynthesis: Epoxidation of toluquinol and gentisyl alcohol by particulate preparations from Penicillium patulum
- Florida State Univ., Tallahassee (USA)
A crude extract that catalyzes the epoxidation of toluquinol and gentisyl alcohol was isolated from cultures of Penicillium patulum. About 60% of the activity sedimented from crude extract upon centrifugation at 105000g for 2 h, and at 30000g for 30 min after precipitation with 30% ammonium sulfate and resuspension in buffer. The quinone epoxide phyllostine, a product of gentisyl alcohol epoxidation, has previously been shown to be an intermediate in the biosynthesis of patulin and was shown to be further converted to neopatulin by the extract. The epoxide product of toluquinol, desoxyphyllostine (2-methyl-5,6-epoxy-1,4-benzoquinone), has not been reported previously from fungal cultures. Its structure was confirmed by GC-mass spectrometry and proton and {sup 13}C NMR. Its CD spectrum showed the same shape and signs as that of phyllostine, indicating that it too is an enzymatic product with a similar absolute configuration. Whereas chemical epoxidation of toluquinone and gentisly quinone occurs with hydrogen peroxide, the enzymatic epoxidation utilized oxygen and the hydroquinone. The epoxidation was inhibited by 1,10-phenanthroline, EDTA, and {rho}-(chloromercuri)benzenesulfonic acid and by degassing with nitrogen, but no inhibition was observed with KCN, catalase, or CO. The apparent K{sub m}'s were similar for the two substrates with both substrates showing inhibition at 1.0 mM. The rate of desoxyphyllostine formation was more than 10 times that of phyllostine formation at equivalent substrate concentrations. Gentisaldehyde was not a substrate for the enzyme. The epoxidase was induced in late fermentor cultures of P. patulum with the same kinetics as m-hydroxybenzyl alcohol dehydrogenase, another enzyme associated with the induction of patulin biosynthesis.
- OSTI ID:
- 6921769
- Journal Information:
- Biochemistry; (USA), Vol. 28:23, Issue 23; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AROMATICS
NUCLEAR MAGNETIC RESONANCE
TOXINS
BIOSYNTHESIS
ALCOHOLS
BIOLOGICAL PATHWAYS
CARBON 13
EPOXIDES
HYDROGEN PEROXIDE
MUTANTS
OXIDATION
PENICILLIUM
THIN-LAYER CHROMATOGRAPHY
ANTIGENS
CARBON ISOTOPES
CHEMICAL REACTIONS
CHROMATOGRAPHY
EUMYCOTA
EVEN-ODD NUCLEI
FUNGI
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS
NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXYGEN COMPOUNDS
PEROXIDES
PLANTS
RESONANCE
SEPARATION PROCESSES
STABLE ISOTOPES
SYNTHESIS
TOXIC MATERIALS
550201* - Biochemistry- Tracer Techniques