Partial purification and characterization of an esterase from fusarium sporotrichioides

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Abstract
Kinetics analysis of the growth of Fusarium sporotrichioides T-424 at 15°C and 25°C in liquid culture for 35 days revealed that production of deacetylated trichothecenes was associated with an increased activity in fungal esterases High temperature (25°C) favored enzyme production and enhanced esterase activity. Electrophoresis of crude extracts from the mycelia of F. sporotrichioides T-424 with carboxylesterase staining revealed that several esterases were produced by the fungus. Four carboxylesterase isoenzymes (I-IV) were separated on a DEAE-Sephadex anion exchange column. Type (III) esterase, having activities with the substrate 4-nitrophenylacetate and acetanilide, as well as hydrolytic activity for T-2 toxin and acetyl-T-2 toxin, was partially purified with ammonium sulfate precipitation, immunoaffinity column chromatography, and DEAE-Sephadex A-50 chromatography. The esterase (III) had a molecular weight around 68 kDa in SDS-PAGE. For the deacylation of T-2 toxin and acetyl-T-2 toxin, type (III) esterase had a high specificity for the acetyl group at the C-3 and C-4 positions The Km values for acetyl-T-2 and T-2 toxin were found to be 41.35 μM and 0.38 μM, respectively. The Km value for the acetyl group at C-3 is 110 times greater than for that at C-4