血管紧张素转化酶底物的制备及对肺癌诊断的临床意义

目的建立血管紧张素转化酶（ACE）底物的合成方法，探讨血清ACE活性的测定方法。方法底物制备采用N-羟基琥珀酰亚胺活化酯合成多肽法；建立分光光度法测定ACE的活性。结景底物呋喃丙烯酰苯丙氨酰甘氨酰甘氨酸纯度为99．5％。底物的米氏常数Km为0．25mmol／L，血清ACE活性正常参考值范围46．7～113．3U／L，标本批内和批间平均变异系数分别为3．9％和4．9％。临床检测表明，肺鳞癌、肺腺癌患者血清ACE活性显著下降（P〈0．05）；而肺小细胞癌患者ACE活性没有明显降低（P〉0．05）。结论所合成的底物适用于临床诊断各类肺癌的要求。

Synthesis of substrate for angiotensin-converting enzyme and its value in diagnosis of lung cancer

Objective To establish the synthetic method of the substrate for angiotensin-converting enzyme(ACE),and investigate the assay method of sernm ACE. Methods The substrate was prepared by the use of N-hydroxysuccinimide ester in peptide synthesis,and serum ACE was determined by spectrophotometric assay using suhstrate. Results The substrate of furanacryloyl-phenylalanyl-glycyl-glycine with purity of 99.5% was obtained.The K_m value for the substrate was 0.25 mmol/L,the normal reference interval for serum ACE activity was 46.7 U/L to 113.3 U/L,and the within-run and between-run coefficient of variation(CVs)ranged from 3.9 to 4.9%.The serum ACE activity in patients with squamous carcinoma and adenocarcinoma of lung were significantly decreased(P<0.05),while that in patients with lung small cell carcinoma was not significantly decreased(P>0.05). Conclusion The synthesized substrate could be reliably used as a marker for diagnosis of different lung cancers in clinics.