Matuszewska B, Borchardt R T
Prep Biochem. 1985;15(3):145-57. doi: 10.1080/10826068508062268.
Histamine N-methyltransferase (HMT, EC 2.1.1.8) was purified 8,420-fold in 44% yield from rat kidney. The basic steps in the purification included differential centrifugation, calcium phosphate adsorption, DEAE cellulose chromatography, and affinity chromatography on an S-adenosylhomocysteine-agarose matrix. The resulting protein was homogeneous as determined by gel electrophoresis and was stable for at least five months at -80 degrees C. The apparent molecular weight of the enzyme was found to be 31,500 as determined by gel filtration through Sephadex G-100 and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point of the enzyme was determined to be 5.4. The Km's for histamine and S-adenosyl-L-methionine were 12.4 +/- 1.3 microM and 10.2 +/- 0.5 microM, respectively. When S-adenosyl-L-methionine was the variable substrate, the Ki's for S-adenosyl-L-homocysteine and S-adenosyl-D-homocysteine were 31.9 +/- 3.4 microM and 32.0 +/- 3.5 microM, respectively. When histamine was the variable substrate, the Ki for S-adenosyl-L-homocysteine was 11.8 +/- 0.6 microM. Comparison of physico-chemical and catalytic properties of the rat kidney and the guinea pig enzymes suggest that these proteins have similar structural and catalytic characteristics.
组胺N-甲基转移酶（HMT，EC 2.1.1.8）从大鼠肾脏中纯化，纯化倍数为8420倍，产率为44%。纯化的基本步骤包括差速离心、磷酸钙吸附、DEAE纤维素色谱以及在S-腺苷同型半胱氨酸-琼脂糖基质上进行亲和色谱。通过凝胶电泳测定，所得蛋白质是均一的，并且在-80℃下至少稳定五个月。通过Sephadex G-100凝胶过滤和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测定，该酶的表观分子量为31,500。该酶的等电点测定为5.4。组胺和S-腺苷-L-甲硫氨酸的Km值分别为12.4±1.3μM和10.2±0.5μM。当S-腺苷-L-甲硫氨酸为可变底物时，S-腺苷-L-同型半胱氨酸和S-腺苷-D-同型半胱氨酸的Ki值分别为31.9±3.4μM和32.0±3.5μM。当组胺为可变底物时，S-腺苷-L-同型半胱氨酸的Ki值为11.8±0.6μM。大鼠肾脏和豚鼠酶的物理化学性质和催化性质比较表明，这些蛋白质具有相似的结构和催化特征。
