ARYLSULFATASE-A IN PSEUDODEFICIENCY
ARYLSULFATASE-A IN PSEUDODEFICIENCY
复制标题
DOI：
10.1007/bf00286589
复制
发表时间：
1984-01-01
期刊：
影响因子：
5.3
通讯作者：
BACH, G
中科院分区：
文献类型：
--
作者：
HERZ, B;BACH, G
发现在异染性脑白质营养不良[MLD]患者范围内的健康个体中存在芳基硫酸酯酶A（ASA）缺陷（假芳基硫酸酯酶A缺陷），这些健康个体通常在体外显示ASA水平。在培养的成纤维细胞中研究了ASA在假性缺乏症中的体外性质。残余ASA活性显示出对合成底物的表观Km（2.6mM）、活性的最适pH（pH5.0）和对65 ℃热变性的敏感性。C（t1/2 [半衰期]，10 min）与对照组相似。为了测试低体外活性是否是对均质化程序极端敏感的结果，通过5种不同的技术破坏细胞，包括快速冷冻和解冻、手动均质化、超声处理、轻度渗透压休克和氮气空化;所有这些都产生了假缺陷与对照的相似ASA比率。使用抗蛋白酶苯甲基磺酰氟和亮抑酶肽没有影响残留的AS活性的假缺陷线。在这种条件下形成的ASA显然具有与正常水解酶相似的性质，因此即使它以较低的量合成，它仍然足以促进硫苷脂的正常催化。筛选ASA活性的淋巴细胞提取物的随机样本的250个人发现7个人的酶水平在MLD杂合子范围或更低。这些个体显然代表假缺陷（PD/PD）的纯合性。在一般人群中，假缺陷等位基因的频率显然约为15%，导致ASA的多态性。
Arylsulfatase A (ASA) is found to be deficient in healthy individuals (pseudo arylsulfatase A deficiency) who usually show in vitro ASA levels in the range of metachromatic leukodystrophy [MLD] patients. The in vitro properties of ASA in pseudodeficiency were studied in cultured fibroblasts. The residual ASA activity showed apparent Km with the synthetic substrate (2.6 mM), pH optimum of activity (pH 5.0) and sensitivity to heat denaturation at 65.degree. C (t1/2 [half time], 10 min) similar to those found in controls. To test whether the low in vitro activity is a result of extreme sensitivity to the homogenization procedure, cells were disrupted by 5 different techniques, including rapid freezing and thawing, hand homogenization, ultrasonication, mild osmotic shock and nitrogen cavitation; all yielded similar ASA ratio of the pseudodeficient to control. The use of antiproteases phenylmethylsulfonyl fluoride and leupeptin did not affect the residual AS activity in the pseudodeficient line. The ASA that is formed in this condition apparently has properties similar to those of the normal hydrolase, so that even if it is synthesized in lower amounts, it is still sufficient to promote normal catabolism of sulfatide. Screening for ASA activity in lymphocyte extracts of a random sample of 250 individuals revealed 7 individuals with enzyme level in the MLD heterozygote range or lower. These individuals apparently represent homozygosity for pseudodeficiency (pd/pd). The frequency of the pseudodeficient allele is apparently about 15% in the general population, leading to polymorphism of the ASA.