Tyce G M, Sharpless N S, Owen C A
Am J Physiol. 1978 Aug;235(2):E150-7. doi: 10.1152/ajpendo.1978.235.2.E150.
A reaction is described in erythrocytes of rat and of man whereby O-methylated metabolites of the catecholamines are demethylated to the corresponding catechols. The reaction was studied by incubating aliquots of erythrocyte lysates with radiolabeled O-methylated compounds and isolating the catechol product by alumina adsorption chromatography. The demethylating activity was located in the cytosol of the erythrocytes. Evidence was strong that oxyhemoglobin was responsible for the reaction: the demethylase activity was inseparable from oxyhemoglobin in several chromatographic separations. In addition, although commercially available hemoglobins were inactive in the reactions, after their conversion to oxyhemoglobin and purification, they did effect demethylation. Methemoglobin did not demethylate guaiacols and in fact inhibited demethylation by oxyhemoglobin. The reaction was inhibited by the addition of reduced pyridine nucleotides and of the methyl acceptor tetrahydrofolic acid.
在大鼠和人的红细胞中描述了一种反应，儿茶酚胺的O-甲基化代谢产物在该反应中被脱甲基化为相应的儿茶酚。通过将红细胞裂解物的等分试样与放射性标记的O-甲基化化合物一起孵育，并通过氧化铝吸附色谱法分离儿茶酚产物来研究该反应。脱甲基活性位于红细胞的胞质溶胶中。有充分证据表明氧合血红蛋白是该反应的原因：在几次色谱分离中，脱甲基酶活性与氧合血红蛋白不可分离。此外，虽然市售血红蛋白在反应中无活性，但在将它们转化为氧合血红蛋白并纯化后，它们确实会产生脱甲基作用。高铁血红蛋白不会使愈创木酚脱甲基化，实际上还会抑制氧合血红蛋白的脱甲基作用。添加还原型吡啶核苷酸和甲基受体四氢叶酸会抑制该反应。
