Isolation, purification and characterization of enzyme(s) responsible for .conversion of sterigmatocystin to aflatoxin B1

Reda I. Mashaly, Samy L. Habib, Samy A. El-Deeb, Mohamed H. Salem, Mohamed M. Safwat

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The cell-free extract prepared from Aspergillus flavus ATCC 5517/A 228 showed activity in converting sterigmatocystin to aflatoxin B1. The extract was purified on Ultrogel AcA-54 and resulted in ten protein peaks, one of which (peak VI) showed activity in sterigmatocystin conversion. The protein in this peak gave one protein band using polyacrylamide gel (PAG)-disc electrophoresis. For further purification, protein(s) in peak VI were applied on DEAE-Sephadex A-50 and two protein peaks were detected. Only one peak showed enzyme activity which showed homogeneity as one band on PAGE and sodium dodecyl sulphate (SDS)-PAGE. The optimum temperature for the enzyme activity was 28 °C and the optimum pH was 8. The maximum conversion resulted from the action of 0.6 mg enzyme protein on 48 × 10-8mol Sterigmatocystin. Zn2+, Co2+ and Mn2+ enhanced the enzyme acitivity, while ethylenediaminetetraacetic acid, parahydroxymercuric benzoate and phenylmethylsulphonic fluoride inhibited the enzyme activity in a dose-dependent manner. Amino-acid analysis showed the presence of 22 amino acids, three of which are unknown. The enzyme has a molecular weight of 64,000 daltons (by gel filtration) and 70,000 daltons (by SDS-PAGE).

Original languageEnglish (US)
Pages (from-to)118-124
Number of pages7
JournalZeitschrift für Lebensmittel-Untersuchung und -Forschung
Volume186
Issue number2
DOIs
StatePublished - Feb 1 1988
Externally publishedYes

ASJC Scopus subject areas

  • Food Science

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