遗传性红细胞嘧啶5’核苷酸酶变异型——P5′N广州型的鉴定

CHARACTERIZATION OF HEREDITARY ERYTHROCYTE PYRIMIDINE-5'-NUCLEOTIDASE VARIANT GUANGZHOU (P5'N GUANGZHOU)

红细胞嘧啶5'核苷酸酶(P5'N)遗传性缺乏是导致溶血性贫血的重要原因之一。在报道我国首例病例的基础上,对P5'N变异型进行了鉴定。结果显示该P5'N变异型具有如下特征:酶活性降低,同类底物利用率改变,热稳定性降低,KmUMP增高,pH曲线改变及最适pH移至碱性。与已报告的P5'N变异型比较,该变异型为一新的变异型,命名为P5'N广州型(P5'N GuangZhou)。

Hereditary erythrocyte pyrimidine-5'-nuclcotidase (P5'N) deficiency is considered as one of the most common erythroenzymopathies. The first case of this disorder was reported else where by the authors, and the chemical dynamic properties of P5'N is presented in this paper. Human erythroeyte P5'N was partially purified by DEAE-cellulose column chromatography and the P5'N was characterized by using five enzyme kinetic parameters. The data of 8 healthy normal Chinese showed (1) the P5'N activity range was 13.5±3.48 (μmol/LPi/hr/gHb); (2) the substrate analogues utilization rate of CMP, 2dUMP, 2dCMP, AMP and TMP were 80.0±3.06%, 301.4±43.53%, 100.3±4.80%, 49.9±13.28% and 723.4±174.11% respectively; (3) the thermal stability of normal P5'N was 86.2±4.39% the Machaelis constant (Km) for UMP was 0.88±0.20mmol/L; (5) the pH optimun was 7.5±0.5. the P5'N activity of the patient was only 4.7 μmol/L Pi/hr/gHb; the mutant enzyme possessed the following properties: an altered analogues utilzation rates, a decreased thermostability, a high Km for UMP and a basic optimal pH. As compared with the variants so far reported, this variant was considered as a new variant designated as P5'N Guangzhou.