Sano A, Endo N, Takitani S
Faculty of Pharmaceutical Sciences, Science University of Tokyo, Japan.
Biol Pharm Bull. 1993 Mar;16(3):304-6. doi: 10.1248/bpb.16.304.
A fluorometric method for the assay of rat brain N-methyltransferase (NMT) has been developed using rat brain 9000 x g supernatant fluid as an enzyme preparation. The method is based on the enzyme reaction at pH 8.6 using 4-methylnicotinamide (4-MN) as the methyl acceptor substrate in the presence of cofactor S-adenosyl-L-methionine (AdoMet), and the fluorometric determination of the product 1,4-dimethylnicotinamide by means of its reaction with 4-methoxybenzaldehyde. The apparent Km values for 4-MN and AdoMet were 0.47 mM and 19 microM, respectively. The method was successfully applied to the studies of age- and sex-related differences of brain NMT activity in rats. The enzyme activity decreased gradually between 3 and 14 weeks of age whereas there were no differences between males and females in the levels of NMT activity.
已开发出一种荧光法来测定大鼠脑N-甲基转移酶（NMT），该方法使用大鼠脑9000×g上清液作为酶制剂。该方法基于在pH 8.6的酶反应，在辅因子S-腺苷-L-甲硫氨酸（AdoMet）存在下，使用4-甲基烟酰胺（4-MN）作为甲基受体底物，并通过其与4-甲氧基苯甲醛的反应对产物1,4-二甲基烟酰胺进行荧光测定。4-MN和AdoMet的表观Km值分别为0.47 mM和19 μM。该方法已成功应用于大鼠脑NMT活性的年龄和性别相关差异研究。酶活性在3至14周龄之间逐渐降低，而NMT活性水平在雄性和雌性之间没有差异。
