鸟嘌呤脱氨酶速率法测定及其对肝病的诊断价值

目的通过速率法测定鸟嘌呤脱氨酶（GD）活性,探讨GD活性对肝病的特异性诊断意义。方法利用GD催化鸟嘌呤生成黄嘌呤,偶联黄嘌呤氧化酶（XOD）生成H2O2,经过氧化物酶（POD）作用与4-氨基安替比林（4-AAP）及2,4-二氯酚作用生成醌亚胺化合物,从而建立测定GD活性的速率测定法。结果该方法重复性良好,批内度异系数（CV）为2.53%,批间CV为3.57%。最适pH值为7.0,Km=1.09×10^-2mmol/L。线性在13.50U/L以下。健康人GD活性呈偏态分布,第95百分位数（P95）〈1.08U/L。急性黄疸型肝炎和继发性肝癌患者GD活性明显增高,其阳性率分别98%和96%。结论该方法快速,精密度高,适用于自动生化分析仪,使GD能成为临床常规测定项目。GD活性增高对肝实质细胞性急性损害有较高的特异性诊断价值,优于丙氨酸氨基转移酶（ALT）等肝功能酶项目测定。

Determination of guanine deaminase by rate method and its diagnostic value to liver diseases

Objective To determine the activity of guanine deaminase （ GD） by rate method and investigate the specificity diagnostic value of GD activity in liver diseases. Methods Xanthine was obtained through the catalysis of guanine by GD. H2O2 was formed by the couple of xanthine oxidase （ XOD）. The actions of peroxidase （ POD） and 4-aminoantipyrine （ 4-AAP） and 2,4-dichlorophen producted quinone imine. The rate method of determining GD activity was established. Results The reproducibility of the method was good. The between-run and within-run coefficients of variation （ CV） were 3. 57% and 2. 53% ,respectively. The optimal pH was 7. 0. The Km was 1. 09 × 10 -2 mmol/L. The linear range was below 13. 50 U/L. The activity of GD in healthy subjects was skew distribution,which the 95th percentile （ P95） was 1. 08 U/L. The activities of GD in the patients with acute icteric hepatitis and secondary liver carcinoma increased significantly. The positive rates were 98% and 96% ,respectively. Conclusions This method is rapid and accurate. It is suitable for automatic biochemical analyzers. The determination of GD can become a clinical routine item. The specificity of GD for liver parenchyma cellular acute lesion is better than that of other indicators,like alanine aminotransferase （ ALT）.