The study aimed to investigate the enzymatic properties of agarase which extracted and separated from a marine bacterium Vibrio natriegens HJPHYXJ-1. The SDS-PAGE grade agarase was derived from fermentation broth, which characterized by refrigerated centrifugations, (NH4)2SO4salting out, DEAE-Sepharose fast flow anion exchange chromatography and Sephacryl S-100 purification. The results showed a yield of 4.4% and the molecular weight of 33.8 kDa while the purification factor was 14.36. More characterizations of agarase indicated that the optimal conditions for agarase were 45 ℃, pH 8.5 and agar concentration of 0.5%. Kmand Vmaxof agarase were 12.24 mg/mL and 0.051 mmol/(L·min), respectively. Agarase was highly specific for agar and its hydrolysates were neoagaro-oligosaccharides with degree of polymerization 2~12 after 5 h degradation.%从海洋细菌Vibrio natriegens HJPHYXJ-1发酵液中提取、分离纯化琼胶酶,研究其酶学性质并对降解产物进行分析.发酵液经离心、(NH4)2SO4沉淀、DEAE-Sepharose Fast Flow阴离子交换层析和Sephacryl S-100凝胶过滤等纯化步骤得到SDS-PAGE电泳级纯酶.酶纯化倍数为14.36,回收率为4.4%,分子量约为33.8 kDa.琼胶酶的最适反应条件:温度为45 ℃,反应pH为8.5,底物浓度为0.5%;琼胶酶的动力学参数Km和Vmax分别为12.24 mg/mL和0.051 mmol/(L·min),对琼胶底物具有高效专一性,经高效液相色谱法(HPLC)分析,当降解反应5 h时,酶解产物主要为分子聚合度2~12之间的新琼寡糖.
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