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Inhibition of protein methyltransferases II from human erythrocytes by S-adenosyl-L-homocysteine and structurally related molecules

par Looze, Yvan ;Gillet, Laurent;Deconinck, Marc Melchior ;Leonis, José
Référence Archives internationales de physiologie et de biochimie, 87, 3, page (632-633)
Publication Publié, 1979

Article révisé par les pairs

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Résumé :

Protein methyltransferase II catalyses the transformation of carboxyl functions of proteins in their methyl-esters. The responsible enzyme was recently obtained from horse erythrocytes and structurally analysed. To characterise the active side of protein methyltransferase II, different analogues of S-adenosyl-L-homocystein (the natural inhibitor of methylases) were synthesized and their binding to the enzyme was measured. S-adenosyl-L-homocystein was found to be the most active inhibitor (Ki - 0.1 M). Modifications of the sulphur atom reduced the Ki value. More essential losses in inhibition were found after the use of amino acid substitutes in the natural inhibitors. Most (probably all) of the examined compounds were inhibitors. It was therefore concluded that the amino acid part of S-adenosyl-L-homocystein contributes to the enzyme binding, though a contribution can be expected from the base and ribose units.