Aspergillus niger 의 Acid Phophatase 효소 정제 및 특성 연구 = Purification and Characterization of Repressible Acid Phosphatase from Aspergillus niger

다국어 초록 (Multilingual Abstract)

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 5.0 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 en several phosphomonoesters as in the case of E. toll system. The Km values for pni trophenyl phosphate were 5.3 × 10^(-4)M and 2.5 × 10^(-4)M with phosphatase 1 and 11 , respectively. Both forms of the enzyme did not shored any metal ion requirement for their activity, but inhibited by inorganic phosphate, Ki values on the hydrolysis of p-nitrophenyl phosphate were 2.6 × 10^(-3)M and 3.8 × 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