Schwelberger H G, Bodner E
Labor für Theoretische Chirurgie, II. Univ.-Klinik für Chirurgie, Universität Innsbruck, Austria.
Biochim Biophys Acta. 1997 Jun 20;1340(1):152-64. doi: 10.1016/s0167-4838(97)00039-3.
Diamine oxidase, the enzyme catalyzing the oxidative deamination of histamine and other diamines, was purified from porcine kidney and porcine intestine. During all purification steps the enzymes from both tissues showed identical binding and elution characteristics. The native enzymes are homodimeric glycoproteins with an apparent molecular weight of 186 kDa. Under reducing conditions the subunits migrate at 104 kDa on SDS polyacrylamide gels and the deglycosylated subunits migrate at 93 kDa which corresponds to a carbohydrate content of 11%. The native and deglycosylated forms of kidney and intestinal diamine oxidase migrate to the same positions, respectively, on two-dimensional isoelectric focussing/SDS polyacrylamide gels. The sequences of the 21 N-terminal amino acids of both proteins are identical. A polyclonal antibody raised against the kidney enzyme binds equally well to diamine oxidase from both kidney and intestine, inhibits the enzymatic activity, and precipitates all diamine oxidase activity from tissue homogenates. The kidney and intestinal enzymes have identical substrate specificities, efficiently converting aliphatic diamines, histamine, and spermidine. For both enzymes the Km values for histamine, putrescine, and spermidine are 0.02 mM, 0.35 mM, and 3.3 mM, respectively. Spermine, aliphatic monoamines, and aromatic mono- and diamines are poor substrates. In conclusion, the diamine oxidase proteins from porcine kidney and intestine are very likely identical and constitute the only diamine oxidase activity present in these tissues. The structural identity implies identical functions of the proteins in these organs, namely the protection of the organism against high concentrations of diamines.
二胺氧化酶是一种催化组胺和其他二胺氧化脱氨反应的酶，已从猪肾和猪小肠中纯化出来。在所有纯化步骤中，来自这两种组织的酶都表现出相同的结合和洗脱特性。天然酶是同型二聚体糖蛋白，表观分子量为186 kDa。在还原条件下，亚基在SDS聚丙烯酰胺凝胶上以104 kDa迁移，去糖基化亚基以93 kDa迁移，这相当于碳水化合物含量为11%。肾和肠二胺氧化酶的天然形式和去糖基化形式在二维等电聚焦/SDS聚丙烯酰胺凝胶上分别迁移到相同位置。两种蛋白质的21个N端氨基酸序列相同。针对肾酶产生的多克隆抗体与肾和肠中的二胺氧化酶结合效果相同，抑制酶活性，并沉淀组织匀浆中的所有二胺氧化酶活性。肾和肠中的酶具有相同的底物特异性，能有效转化脂肪族二胺、组胺和亚精胺。对于这两种酶，组胺、腐胺和亚精胺的Km值分别为0.02 mM、0.35 mM和3.3 mM。精胺、脂肪族单胺以及芳香族单胺和二胺是较差的底物。总之，猪肾和小肠中的二胺氧化酶蛋白很可能是相同的，并且是这些组织中唯一存在的二胺氧化酶活性。结构上的一致性意味着这些器官中蛋白质的功能相同，即保护机体免受高浓度二胺的影响。
