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Purification and properties of thioether methyltransferase

Thesis/Dissertation ·
OSTI ID:7245891
A method to assay activity was developed which measures acceptance of methyl groups from (methyl-{sup 3}H)-S-adenosylmethionine by dimethyl selenide. The product, ({sup 3}H)trimethylselenonium ion, is separated by HPLC and quantitated by scintillation counting. Thioether methyltransferase from mouse liver and lung resides primarily in the cytosol. In terms of specific activity the enzyme is most active in the lung and liver. Purification from lung cytosol requires a three-step process of DEAE and gel filtration column chromatographies followed by chromatofocusing. SDS-Polyacrylamide gel electrophoresis shows a single homogeneous band with a molecular mass of 28,000 daltons. Vmax and Km values for dimethyl selenide as a substrate are 15. 7 pmol/min and 0.44 {mu}M, respectively. Our studies have also shown that this purified enzyme is capable of methylating a wide range of compounds. To further test the enzyme's role in detoxification, in vivo studies were performed by injecting mice with substrate and (methyl-{sup 3}H)methionine and analyzing tissue extracts and urine for (methyl-{sup 3}H)sulfonium.
Research Organization:
Louisville Univ., KY (USA)
OSTI ID:
7245891
Country of Publication:
United States
Language:
English

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