Rahman M Khalilur, Choudhary M Iqbal, Islam M Rafiqul, Hafizur Rahman M
Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka 1000, Bangladesh;
Int J Biomed Sci. 2012 Sep;8(3):194-203.
Dopoamine-β-hydroxylase (DBH) is a catecholamine-synthesizing enzyme which catalyzes the formation of norepinephrine from dopamine. Fifty nine Long-Evans rats of 1 week-old were used to grow on normal diets in 7 different developmental stages, viz., 15 rats in 1 week-old group, 9 rats in 2 weeks-old group, and the remaining 35 rats were divided equally into five groups, 7 rats in each group of 5-, 8-, 12-, 15- and 27-weeks old for systematic developmental studies of DBH. At the end of each developmental period, weights of rats were recorded for that specific group and they were sacrificed. The brain tissues (caudate nucleus, hypothalamus, brain stem, colliculi, cerebral cortex and cerebellum) and peripheral tissues (liver, heart, kidney, adrenal, spleen, pancreas, lung and small intestine) and serum were collected. The brain tissues had the highest activity (expressed as nmole/min/g of wet weight tissue) of DBH at 5 weeks of age. The hypothalamus had the highest activities (11.5 ± 2.2) and the lowest activities were found in the cerebellum (5.7 ± 0.9). The peripheral tissues also showed the peak DBH activities at 5 weeks of age and adrenals had the highest activities (59.2 ± 7.0) among the central and peripheral tissues. The serum DBH activities were relatively low (1.3 ± 0.2) as compared to those in all other tissues. The highest serum DBH activities (1.28 ± 21 nmole/min/ml of serum) were also found in the 5- weeks-old rats. The specific activities of DBH were also measured in various developmental stages and the results were found to be in agreement with the DBH activities expressed in terms of gram of tissues or milliliter of serum. The Km and Vmax values for DBH were measured in the serum samples of each group and the highest Vmax values (78.3 ± 21.2 pmol/min/mg protein) were obtained at 5 weeks of age; while the lowest Km values (0.52 ± 0.04 mM) were obtained at this stage of age.
多巴胺-β-羟化酶（DBH）是一种儿茶酚胺合成酶，可催化多巴胺形成去甲肾上腺素。选用59只1周龄的Long-Evans大鼠，使其在7个不同发育阶段正常饮食，即1周龄组15只大鼠，2周龄组9只大鼠，其余35只大鼠平均分为五组，每组7只，分别为5周龄、8周龄、12周龄、15周龄和27周龄，用于对DBH进行系统发育研究。在每个发育阶段结束时，记录该特定组大鼠的体重，然后将其处死。收集脑组织（尾状核、下丘脑、脑干、丘、大脑皮层和小脑）、外周组织（肝脏、心脏、肾脏、肾上腺、脾脏、胰腺、肺和小肠）及血清。DBH活性（以每克湿重组织的纳摩尔/分钟表示）在5周龄时的脑组织中最高。下丘脑的活性最高（11.5±2.2），而小脑的活性最低（5.7±0.9）。外周组织在5周龄时也显示出DBH活性峰值，肾上腺在中枢和外周组织中的活性最高（59.2±7.0）。与所有其他组织相比，血清DBH活性相对较低（1.3±0.2）。5周龄大鼠的血清DBH活性也最高（1.28±21纳摩尔/分钟/毫升血清）。还在各个发育阶段测量了DBH的比活性，结果发现与以克组织或毫升血清表示的DBH活性一致。在每组血清样本中测量了DBH的Km和Vmax值，在5周龄时获得最高的Vmax值（78.3±21.2皮摩尔/分钟/毫克蛋白质）；而在该年龄阶段获得最低的Km值（0.52±0.04毫摩尔）。
