Purification and characterization of two agarases from Agarivorans albus OAY02

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• 作者：Meng Yang ; Xiangzhao Mao ; ^{xzhmao@ouc.edu.cn" class="auth_mail} ; Nan Liu ; Yongqian Qiu ; Changhu Xue
• 关键词：Purification ; Characterization ; 尾-Agarase ; Agarivorans ; Neoagaro-oligosaccharide
• 刊名：Process Biochemistry
• 出版年：May, 2014
• 年：2014
• 卷：49
• 期：5
• 页码：905-912
• 全文大小：1793 K

文摘

Two extracellular 尾-agarases were purified from Agarivorans albus OAY2, which was isolated from seaweed collected in Qingdao, Shandong, China. The fermentation process was optimized with enzyme activity improving from 1.06 U/ml to 2.65 U/ml. Agarases were purified by ammonium sulfate fractionation and ion-exchange chromatography. Purification resulted in a 107-fold increase in agarase-a activity and a 52-fold increase in case of agarase-b, with high specific activities of 2715 and 1338 U/mg, respectively. The molecular masses of the agarases were estimated to be 50 kDa and 107 kDa, respectively. The optimum temperatures for the activities of agarase-a and agarase-b were 40 掳C and 50 掳C, respectively. Agarase-a was stable at 30 掳C, while agarase-b was stable at 50 掳C. The optimum pH values for agarase-a and agarase-b were both 9.0. Agarase-a was inhibited by Cu²⁺, Mn²⁺, Co²⁺ and EDTA, while agarase-b was inhibited by Cu²⁺, Mn²⁺ and Fe²⁺. The results of ¹³C NMR and TLC showed that hydrolysis of agarose by agarase-a produced neoagarobiose (NA2), neoagarotetraose (NA4) and neoagarohexaose (NA6). Agarase-b hydrolyzed agarose to yield neoagarobiose (NA2) and neoagarotetraose (NA4). Evaluation of matrix-assisted laser desorption ionization/time-of-flight MS (MALDI-TOF-TOF/MS) and the enzymatic product results indicated that agarase-a and agarase-b might be novel agarases.