水稻酸性磷酸酶

Acid phosphatase in rice seedlings

水稻組織的粗抽出液在電泳分析圖譜上呈現十倍的同功酶。此粗抽出液的循步純化經硫酸銨沉澱法、Ultro膠體過濾法、DEAE-trisacryl色層法及對焦色層法等分析後，取得一與p-nitrophenyl phosphate（pNPP）親和性很高的同功酶。其經FPLC法所定的分子量為130 kD，以SDS-PAGE法定出次單體的分子則分別為70 kD及62 kD。該同功酸性磷酸酶的最適pH為5.0，對pNPP的Km為0.69 mM，屬熱不穩定性酵素，鎂離子及錳離子的存在可加強酵素活性，汞離子屬強抑制劑，氟化鈉則只具部分抑制性。

Acid phosphatase (EC 3. 1. 3. 2) extracted from rice seedlings consisted of ten kinds of isozymes based on separation by polyacryamide gel electrophoresis. One isozyme was purified through ammonium sulfate precipitation, Ultrogel gel filtration, DEAE-trisacryl chromatography and chromatofocusing. This isozyme had a high affinity to p-nitrophenyl phosphate. The molecular weight of this isozyme was around 130 kD examined with FPLC and it consisted of heterodimer with molecular weight of 70 kD and 62 kD. The purified isozyme had a pH optimum at 5.0 and its Km (p-nitrophyenyl phosphate) was 0.69 mM. Mg++ and Mn++ enhanced the activity, but heavy metal ions were inhibitory. NaF and Na2MoO4 also had an inhibitory effect on the isozyme.