Kase R, Hazato T, Shimamura M, Kiuchi Y, Katayama T
Arch Biochem Biophys. 1985 Jul;240(1):330-6. doi: 10.1016/0003-9861(85)90038-4.
A dipeptidyl carboxypeptidase, which cleaved the Gly3-Phe4 bond of enkephalins, was purified from guinea pig serum 420-fold. The optimum pH of the enzyme was in the neutral range (pH 7.25), and the molecular weight was estimated to be approx. 280,000. The enzyme hydrolyzed Met- and Leu-enkephalin with Km values of 0.30 and 0.50 mM, respectively. The enzyme was inhibited by metal chelators and p-chloro-mercuribenzoate. Captopril showed high inhibitory potency, while phosphoramidon and Phe-Ala showed no effect on the enzyme activity. Therefore, the obtained enzyme can be classified as an angiotensin-converting enzyme (EC 3.4.15.1). Among the bioactive peptides examined, bradykinin and angiotensin I were hydrolyzed by the enzyme. Angiotensin III showed a stronger inhibitory effect than that of angiotensin II. Substance P, gastrin I, and secretin were also inhibitory toward the enzyme activity. On high-performance liquid chromatography analysis, Met-enkephalin-Arg6-Phe7 and Leu-enkephalin-Arg6 were cleaved sequentially at the second peptide bond of the C terminus. Thus, the dipeptidyl carboxypeptidase in guinea pig serum may play a role not only in the angiotensin-bradykinin system but also in the metabolism of circulating enkephalins and other bioactive peptides.
从豚鼠血清中纯化出一种二肽基羧肽酶，该酶可切割脑啡肽的Gly3 - Phe4键，纯化倍数达420倍。该酶的最适pH值在中性范围（pH 7.25），分子量估计约为280,000。该酶水解甲硫氨酸脑啡肽和亮氨酸脑啡肽的Km值分别为0.30和0.50 mM。该酶受到金属螯合剂和对氯汞苯甲酸的抑制。卡托普利显示出高抑制效力，而磷酰胺脒和苯丙氨酸 - 丙氨酸对酶活性无影响。因此，所获得的酶可归类为血管紧张素转换酶（EC 3.4.15.1）。在所检测的生物活性肽中，缓激肽和血管紧张素I可被该酶水解。血管紧张素III的抑制作用比血管紧张素II更强。P物质、胃泌素I和促胰液素也对酶活性有抑制作用。在高效液相色谱分析中，甲硫氨酸脑啡肽 - Arg6 - Phe7和亮氨酸脑啡肽 - Arg6在C末端的第二个肽键处依次被切割。因此，豚鼠血清中的二肽基羧肽酶可能不仅在血管紧张素 - 缓激肽系统中起作用，还在循环脑啡肽和其他生物活性肽的代谢中起作用。
