A dipeptidyl carboxypeptidase which removes the c-terminus and penultimate a dipeptide from substrate molecules was isolated from the hog lung and was purified by ammonium sulfate fractionation, Sephadex G-150 gel filtration, DEAE-cellulose chromatography and hydroxyapatite column chromatography. A partially purified enzyme preparation showed a specific activity of 2.1 umole of dipeptide produced per minute per mg protein. The approximate molecular weight of the enzyme was about 170,000 based the gel filtration. The enzyme released dipeptide from the c-terminal end of a various peptide substrated, including N-blocked tripeptides, angiotensin I, and bradykinin. The Km for Z-Phe-GlyGly was 0.66mM at the optimum $p^H$ of 8.0 under the presence of 0.1M Nacl. The presence of metal chelators, EDTA, o-phenanthroline, inhibited the enzyme activity but the addition of the required metal ions, Zn, Co, Mg, and Ma.
From the fact that the enzyme is capable to hydrolyze both of angiotensin I and bradykinin which are the most important kinin hormones, the participation of the enzyme to the blood pressure control mechanism in the pulmonary circulating system was suggested.
peptide 나 단백질을 기질로 이용하여 C-terminal에서 dipeptide을 생성하는 dipeptidyl carboxypeptidase를 돼지의 허파에서 추출하여 황산암모늄염 처리, Sep-G-150을 이용한 Gel여과, DEAE-cellulose에 의한 이온 교환체 및 Hydroxyapatite에 흡착시켜서 얻어진 부분정제된 효소의 비활성도는 2.1μmole/min/mg protein이었다. 이 효소의 분자량은 170,000으로서 N terminal의 $NH_2$ 잔기를 치환시킨 tripeptide, angiotensin I 및 bradykinin을 가수분해시킨다. 또한 Cl-이 존재하는 pH8.0의 인산나트륨 완충액에서 기질 Z-Phe-Gly-Gly에 대한 효소의 Km은 0.66mM이었으며 EDTA에 의해서 완전히 활성이 저해된 효소가 Zn,Co 및 Mg 같은 금속이온을 첨가시킴으로써 재 활성화되었다. 한편 이 효소가 angiotensin I과 bradykinin을 함께 가수분해하는 사실로서 혈압을 조절하는데 있어서 이 효소의 반응이 관여할 것으로 믿어진다.
