A novel thermophilic exochitinase ChiEn3 from Coprinopsis cinerea exhibits a hyperhydrolytic activity toward 85% deacetylated chitosan and a significant application to preparation of chitooligosaccharides from the chitosan

• Published in: Carbohydrate polymers Vol. 207; pp. 729 - 736
• Main Authors: Zhou, Jiangsheng, Dai, Rujuan, Wang, Yanxin, Li, Maomao, Zhu, Yiting, Chen, Lingling, Kang, Liqin, Liu, Zhonghua, Yang, Yao, Yuan, Sheng
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2019
• Subjects: 85% deacetylated chitosan; Agaricales - enzymology; Amino Acid Sequence; Anti-oxidant activity; Antioxidants - chemical synthesis; Antioxidants - chemistry; Base Sequence; Chitin - analogs & derivatives; Chitin - chemical synthesis; Chitin - chemistry; Chitinases - chemistry; Chitinases - isolation & purification; Chitooligosaccharides; Chitosan - chemistry; Exochitinase; Fungal Proteins - chemistry; Fungal Proteins - isolation & purification; Hydrolysis; Protein Conformation; Thermophilicity; Exochitinase; 85% deacetylated chitosan; Anti-oxidant activity; Chitooligosaccharides; Thermophilicity
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2018.12.047

•ChiEn3 was an exochitinase with a processive mode of action.•ChiEn3 hydrolyzed only soluble chitin (not insoluble chitin substrates).•ChiEn3 showed hyperhydrolytic activity toward 85% deacetylated chitosan.•ChiEn3-digested products of 85% deacetylated chitosan had high antioxidant activity.•ChiEn3 showed remarkable thermophilicity. ChiEn3 from Coprinopsis cinerea was characterized as an exo-acting chitinase with a processivity. ChiEn3 hydrolyzed only soluble chitin and exhibited a hyperhydrolytic activity toward 85% deacetylated chitosan which was 33.6-fold higher than its hydrolytic activity toward glycol chitin. Its maximum hydrolytic activity was observed at 60 °C and retained 66.2% of hydrolytic activity after 60 min incubation at 60 °C. Commercial 85% deacetylated chitosan was degraded by ChiEn3 to a series of COSs with a DP of 2–20 in which COSs with a DP of 3–6 were dominant, whereas, lab-prepared chitosan (FA = 0.65) was degraded by ChiEn3 to COSs with a DP of 2–10 in which the AA dimer was dominant. DPPH-radical-scavenging activity of ChiEn3-digested products of 85% deacetylated chitosan was 3.32-fold higher than that of undigested 85% deacetylated chitosan. Therefore, ChiEn3 shows a valuable advantage for application to the preparation of COSs from commercial 85% deacetylated chitosan.