CalkGH9T: A Glycoside Hydrolase Family 9 Enzyme from Clostridium alkalicellulosi

Catalysts

Khanok Ratanakhanokchai¹  Sengthong Lee¹  Techly San¹  Paripok Phitsuwan² 

[1] Division of Biochemical Technology, School of Bioresources and Technology, King Mongkut′s University of Technology Thonburi, Bangkok 10150, Thailand;LigniTech-Liginin Technology Research Group, School of Bioresources and Technology, King Mongkut′s University of Technology Thonburi, Bangkok 10150, Thailand;

关键词: carbohydrate binding module;    crystalline cellulose;    endoglucanase;    processive activity;   

DOI  :  10.3390/catal11081011

来源: DOAJ

【 摘 要 】

Glycoside hydrolase family 9 (GH9) endoglucanases are important enzymes for cellulose degradation. However, their activity on cellulose is diverse. Here, we cloned and expressed one GH9 enzyme (CalkGH9T) from Clostridium alkalicellulosi in Escherichia coli. CalkGH9T has a modular structure, containing one GH9 catalytic module, two family 3 carbohydrate binding modules, and one type I dockerin domain. CalkGH9T exhibited maximal activity at pH 7.0–8.0 and 55 °C and was resistant to urea and NaCl. It efficiently hydrolyzed carboxymethyl cellulose (CMC) but poorly degraded regenerated amorphous cellulose (RAC). Despite strongly binding to Avicel, CalkGH9T lacked the ability to hydrolyze this substrate. The hydrolysis of CMC by CalkGH9T produced a series of cello-oligomers, with cellotetraose being preferentially released. Similar proportions of soluble and insoluble reducing ends generated by hydrolysis of RAC indicated non-processive activity. Our study extends our knowledge of the molecular mechanism of cellulose hydrolysis by GH9 family endoglucanases with industrial relevance.

【 授权许可】

Unknown