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Purification of mixed-function amine oxidase from rat liver microsomes
Biochemical and Biophysical Research Communications
|January 27, 1983
Summary
Researchers purified mixed function amine oxidase (MFAO) from rat liver to understand carcinogenic aminoazo dye metabolism. The enzyme, with a molecular weight of 59,000, metabolizes dimethylaniline (DMA) and dimethylaminoazobenzene (DAB) in the presence of NADPH and iron.
Area of Science:
- Biochemistry
- Enzymology
- Toxicology
Background:
- Carcinogenic aminoazo dyes are metabolized in target tissues.
- Understanding the enzymes involved is crucial for assessing health risks.
Purpose of the Study:
- To purify and characterize mixed function amine oxidase (MFAO) from rat liver.
- To investigate the enzyme's role in the metabolism of carcinogenic aminoazo dyes.
Main Methods:
- Microsomal solubilization using Triton X, glycerol, and EDTA.
- Purification via sequential column chromatography (DEAE Sepharose CL-6B, 2',5'-ADP Sepharose 4B, Hydroxyapatite).
- Enzyme activity assays using dimethylaniline (DMA) and dimethylaminoazobenzene (DAB) as substrates, with SDS-PAGE for purity assessment.
Main Results:
- A single protein band (59,000 MW) was obtained after purification, indicating high enzyme purity.
- Purified MFAO exhibited specific activity of ~430 nmol DMA N-oxide/mg protein/min with NADPH.
- N-demethylation of DAB by MFAO required the addition of iron to the reaction system.
Conclusions:
- Rat liver MFAO is a key enzyme in aminoazo dye metabolism.
- The enzyme's activity is dependent on cofactors like NADPH and iron.
- Further studies on MFAO can elucidate mechanisms of dye-induced toxicity.