Hiemke C, Ghraf R
J Neurochem. 1981 Sep;37(3):613-8. doi: 10.1111/j.1471-4159.1982.tb12531.x.
The distribution of methionine adenosyltransferase (MAT) in the CNS of the rat was studied by use of a rapid, sensitive and specific radiochemical method. The S-adenosyl-[methyl-14C]L-methionine ([14C]SAM) generated by adenosyl transfer from ATP to [methyl-14C]L-methionine is quantitated by use of a SAM-consuming transmethylation reaction. Catechol O-methyltransferase (COMT), prepared from rat liver, transfers the methyl-14C group of SAM to 3,4-dihydroxybenzoic acid. The 14C-labelled methylation products, vanillic acid and isovanillic acid, are separated from unreacted methionine by solvent extraction and quantitated by liquid scintillation counting. Compared to other methods of MAT determination, which include separation of generated SAM from methionine by ion-exchange chromatography, the assay described exhibited the same high degree of specificity and sensitivity but proved to be less time consuming. MAT activity was found to be uniformly distributed between various brain regions and the pituitary gland of adult male rats. In the pineal gland the enzyme activity is about tenfold higher.
采用一种快速、灵敏且特异的放射化学方法，研究了蛋氨酸腺苷转移酶（MAT）在大鼠中枢神经系统中的分布。通过腺苷从ATP转移至[甲基 - 14C]L - 蛋氨酸生成的S - 腺苷 - [甲基 - 14C]L - 蛋氨酸（[14C]SAM），利用一个消耗SAM的转甲基反应进行定量。从大鼠肝脏制备的儿茶酚O - 甲基转移酶（COMT），将SAM的甲基 - 14C基团转移至3,4 - 二羟基苯甲酸。通过溶剂萃取将14C标记的甲基化产物香草酸和异香草酸与未反应的蛋氨酸分离，并通过液体闪烁计数进行定量。与其他MAT测定方法（包括通过离子交换色谱从蛋氨酸中分离生成的SAM）相比，所描述的测定方法具有相同高度的特异性和灵敏度，但被证明耗时更短。发现MAT活性在成年雄性大鼠的各个脑区和垂体之间均匀分布。在松果体中，该酶活性约高十倍。
