Nagaoka Megumi, Shiraishi Takayuki, Furuhata Kimio, Uda Yutaka
Laboratory of Health Chemistry, Faculty of Pharmaceutical Science, Niigata University of Pharmacy and Applied Life Sciences, Japan.
Biol Pharm Bull. 2003 Mar;26(3):295-8. doi: 10.1248/bpb.26.295.
An acid sialidase partially purified from porcine liver was activated by incubation at 37 degrees C under acidic pH. This activation was dependent on pH, time and temperature, but not inhibited by amastatin, an inhibitor of aminopeptidase A, in contrast to the case of human placental sialidase. The effects of inorganic anions on the two sialidases from porcine liver and from human placenta were investigated. Among the anions tested, halide ions, especially chloride and bromide ions, markedly enhanced the activation of the two sialidases. However, nitrate, sulfate, sulfite and pyrosulfite ions rarely affected the activation of sialidase from porcine liver, while all of them enhanced the activation of human placental sialidase. The activation of the enzyme from porcine liver was depressed at concentrations of greater than 100 mM of sodium chloride, whereas the enzyme from human placenta was held at maximum activation until 1 M sodium chloride. These results suggest the possibility of the participation of enzyme functions different from that of human placental sialidase in the activation process of sialidase.
从猪肝中部分纯化得到的酸性唾液酸酶在酸性pH条件下于37℃孵育可被激活。这种激活依赖于pH、时间和温度，但与人类胎盘唾液酸酶的情况不同，它不受氨肽酶A抑制剂氨甲酰抑制剂的抑制。研究了无机阴离子对猪肝和人胎盘两种唾液酸酶的影响。在所测试的阴离子中，卤离子，尤其是氯离子和溴离子，显著增强了这两种唾液酸酶的激活作用。然而，硝酸根、硫酸根、亚硫酸根和焦亚硫酸根离子对猪肝唾液酸酶的激活作用影响很小，而它们都增强了人胎盘唾液酸酶的激活作用。当氯化钠浓度大于100 mM时，猪肝中该酶的激活作用受到抑制，而人胎盘来源的酶在1 M氯化钠浓度下仍保持最大激活状态。这些结果表明，在唾液酸酶的激活过程中，可能存在与人类胎盘唾液酸酶不同的酶功能参与其中。
