낮은 농도의 제한된 무기인산을 함유시킨 배지에 의하여 성장시킨 Aspergillus niger로 부터 서로 다른 성질을 갖는 두 종류의 Acid Phosphatase를 분리하였으며 젤크로마토 그라피 방법에 의한 정제 과정을 통하여 비교적 순수한 효소분획, phosphatase I과 II를 얻을 수 있었다. 이를 효소분획의 분자량은 phosphatase I과 II에 대하여 각각의, 25,000과 40,000으로 얻어졌으며, 효소의 비활성도 각각 1,300과 463 units/mg protein이었다. 효소의 특성 실험결과 이들은 pH optimum(pH 5.0과 pH 3.0~3.5) 최적 활성 온도열에 대한 안정도 및 기질 특이성 등에 있어 각각 상이한 성질을 갖고 있음을 알았으며 특히 phosphatase I 은 p-nitrophenyl phosphate ($Km=5.3{ imes}10^{-4}M$)과 phosphoenol pyrubate등에만 활성을 갖는 specific acid phosphatase로 간주되었으며 반면 phosphatase II는 p-nitrophenyl phosphate ($Km=2.5{ imes}10^{-4}M$)을 포함한 대부분의 phosphomonoester등에 대하여 비교적 좋은 활성도를 나타냄으로서 nonspecific acid phosphomonoesterase로 간주할 수 있었다. 한편 이들 효소의 생화학적 기능과 역할에 대하여도 세포 내 인산화물의 대사와 비교 검토하였으며 무기인산에 의한 효소 생장 촉진 및 효소 활성도의 억제 현상과도 비교 고찰하였다.
Two forms of inorganic phosphate repressible acid phosphatase, phosphatase I and II, were fractionated from extracts of the mycelium of Aspergillus niger grown under the limited phosphate medium, and were purified in relatively homogeneous forms having molecular weights of about 25,000 and 40,000 daltons, respectively. Each form of the enzymes showed their distinct properties differing in the pH optimum and substrate specificity. Phosphatase I showed its optimum activity at pH 5. a with p-nitrophenyl phosphate as a substrate while the activity of phosphatase II with the same synthetic substrate showed its optimum pH at 3.0~3.5. In substrate specificity, phosphatase I acted as a highly specific acid phosphatase reacting mostly against p-nitrophenyl phosphate and phosphoenol pyruvate, but phosphatase II as a non-specific acid phophomonoesterase showed a broad specificity on several phosphomonoesters as in the case of E. coli system. The Km values for pnitrophenyl phosphate were $5.3{ imes}10^{-4}M$ and $2.5{ imes}10^{-4}M$ with phosphatase I and II, respectively. Both forms of the enzyme did not showed any metal ion requirement for their activity, but inhibited by inorganic phosphate, Ki values on the hydrolysis of p-nitrophenyl phosphate were $2.6{ imes}10^{-3}M$ and $3.8{ imes}10^{-4}M$ for phosphatase I and II, respectively. The nature and role of acid phosphatase were also discussed in connection with the mycelial growth under the limiting phosphate medium.
