Penicillium sp.DS9701-09分泌的聚β-羟基丁酸酯(PHB)解聚酶的纯化及性质研究

Purification and Properties of a PHB Depolymerase from the Penicillium sp.DS9701-09

以Penicillium sp.DS9701-09为研究对象,对其分泌的PHB解聚酶进行分离纯化和表征.通过超滤浓缩、硫酸铵分级沉淀和Sephadex G-100凝胶过滤,从发酵液中纯化了一种对PHB具有高效降解能力的解聚酶,纯化倍数为37.9,酶活力回收率为8.9%.经SDS-PAGE检测,确定酶蛋白的相对分子质量为41.5 kDa.酶反应的最适温度和pH分别为50℃和5.0,在50℃以下和pH=5.0~6.0之间酶的稳定性较好.金属离子对PHB解聚酶具有一定的抑制作用,降解酶对PHB的酶解产物主要是羟基丁酸二聚体.

The extracellular PHB depolymerase was purified from the culture of Penicillium sp.DS9701-09 by filtration,ammonium sulfate precipitation and chromatography on Sephadex G-100.The specific activity of the purified enzyme was increased by 37.9 folds over crude extract,and the recovery yield was 8.9%.The molecular weight of the PHB depolymerase was about 41.5 kDa.The optimum activity of enzyme was observed at the temperature 50 ℃ and pH 5.0.Different metal ions caused inhibition on the PHB depolymerase activity.The mass spectrum analysis confirmed that the main hydrolysis product soluble in water of PHB by PHB depolymerase was 3-hydroxybutyrate dimer.