Addition of methyl groups; in histochemistry, used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid; the net effect being to reduce tissue basophilia and abolish metachromasia.
- restriction m. the enzymatic addition of methyl groups to selected adenine and cytosine residues to protect from hydrolysis by certain restriction enzymes.
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meth·yl·ation .meth-ə-'lā-shən n introduction of the methyl group into a chemical compound esp dna methylation
meth·yl·ate 'meth-ə-.lāt vt, -at·ed; -at·ing
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meth·yl·a·tion (meth″əl-aґshən) addition of one or more methyl groups to a substance.Medical dictionary. 2011.