Purification and characterization of two endoglucanases from Melanocarpus sp MTCC 3922
Purification and characterization of two endoglucanases from Melanocarpus sp MTCC 3922
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DOI：
10.1016/j.biortech.2005.11.019
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发表时间：
2007-01-01
影响因子：
11.4
通讯作者：
Saini, Harvinder S.
中科院分区：
文献类型：
--
作者：
Kaur, Jatinder;Chadha, Bhupinder S.;Saini, Harvinder S.
本研究报道了从新分离的嗜热真菌Melanocarpus sp. MTCC 3922中纯化和鉴定内切葡聚糖酶（EG I和EG II）。EG I和EG II与SDS-PAGE和pI的分子量分别接近于40和50 kDa，接近于4.0和3.6。EG I和EG II分别在50℃和70℃、pH 6.0和5.0条件下活性最佳。EG I在较宽的pH（5.0-7.0）范围内具有活性，而随着温度从50℃升高到80℃，活性下降，而EG II在pH 4.0-6.0和温度40-80℃范围内具有活性。巯基乙醇和SDS的存在抑制了EG I的活性，但对EG II没有负面影响。两种内切葡聚糖酶对大麦-葡聚糖的抑制活性均高于CMC。大麦- β -葡聚糖的EG I和EG II的K-m值低于CMC。以大麦- β -葡聚糖为底物时，两种内切葡聚糖酶的翻转数（K-cat）和催化效率（K-cat/K-m）均高于CMC。EG I对Avicel表现出亲和力，表明存在纤维素结合域（CBD），而EG II则缺乏CBD。(c) 2005 Elsevier Ltd版权所有。
This study reports the purification and characterization of endoglucanases (EG I and EG II) from a newly isolated thermophilic fungus, Melanocarpus sp. MTCC 3922. The molecular weight of EG I and EG II as with SDS-PAGE and pI were similar to 40 and 50 kDa, and similar to 4.0 and 3.6, respectively. EG I and EG II were optimally active at 50 and 70 degrees C, and pH 6.0 and 5.0, respectively. EG I was active over a broad range of pH (5.0-7.0), whereas, loss of activity was observed as the temperature was increased from 50 to 80 degrees C. However, EG II was active over pH 4.0-6.0 and temperature 40-80 degrees C. The presence of mercaptoethanol and SDS inhibited the EG I activity but showed no negative effect on EG II. Both the endoglucanases showed higher activity against barley-beta-glucan as compared to CMC. K-m values of EG I and EG II for barley-beta-glucan were lower than CMC. Turn over number (K-cat) and catalytic efficiency (K-cat/K-m) values of both the endoglucanases were higher with barley-beta-glucan as substrate than CMC. EG I showed affinity for Avicel indicating the presence of cellulose binding domains (CBD) whereas, EG II was found to lack CBD. (c) 2005 Elsevier Ltd. All rights reserved.