title: DNA methylation by wheat cytosine DNA methyltransferase: modulation by protease inhibitor E-64.
abstract: Cytosine DNA methyltransferase isolated from wheat seedlings and purified in the presence of metalloprotease and serine protease inhibitors has molecular mass and specific activity equal to about 85 kDa and 250 units/mg protein, respectively. Apparent K(m) for AdoMet and [I]50 for AdoHcy values are about 6 microM and 12 microM, respectively. The enzyme is active in wide pH range (pH 5.5-8.5) and is inhibited by NaCl. The enzyme rapidly loses its methyltransferase activity in the absence of substrates. Using the cysteine protease inhibitor E-64 it has been shown that rapid enzyme inactivation is caused by disappearance of essential enzyme SH-groups but is not due to proteolytic enzyme cleavage.
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Russia. vlasova@libro.genebee.msu.su
authors.forename: T I
authors.initials: TI
authors.lastname: Vlasova
authors.forename: B F
authors.initials: BF
authors.lastname: Vanyushin
mesh_terms: D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D019175:DNA Methylation / Q000187:drug effects*; D004269:DNA, Bacterial / Q000378:metabolism; D018744:DNA, Plant / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D007930:Leucine / Q000031:analogs & derivatives* / Q000187:drug effects / Q000494:pharmacology; D008970:Molecular Weight; D010944:Plants / Q000201:enzymology; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000378:metabolism; D014908:Triticum / Q000201:enzymology*
chemical_list: D015853:Cysteine Proteinase Inhibitors; D004269:DNA, Bacterial; D018744:DNA, Plant; D013438:Sulfhydryl Compounds; D004248:DNA (Cytosine-5-)-Methyltransferases; D007930:Leucine; C024974:E 64; D004229:Dithiothreitol