壳聚糖酶
米曲霉
壳聚糖
甲壳素
酶
化学
黄曲霉
生物化学
米根霉
氨基葡萄糖
曲霉
水解
几丁质酶
低聚物
微生物学
生物
发酵
食品科学
有机化学
作者
Xiao‐Yong Zhang,Anlan Dai,Xuekun Zhang,Kouji Kuroiwa,Ritsuko Kodaira,Makoto Shimosaka,Mitsuo Okazaki
摘要
Chitosan-degrading activity was detected in the culture fluid of Aspergillus oryzae, A. sojae, and A. flavus among various fungal strains belonging to the genus Aspergillus. One of the strong producers, A. oryzae IAM2660 had a higher level of chitosanolytic activity when N-acetylglucosamine (GlcNAc) was used as a carbon source. Two chitosanolytic enzymes, 40 kDa and 135 kDa in molecular masses, were purified from the culture fluid of A. oryzae IAM2660. Viscosimetric assay and an analysis of reaction products by thin-layer chromatography clearly indicated the endo- and exo-type cleavage manner for the 40-kDa and 135-kDa enzymes, respectively. The 40-kDa enzyme, designated chitosanase, catalyzed a hydrolysis of glucosamine (GlcN) oligomers larger than pentamer, glycol chitosan, and chitosan with a low degree of acetylation (0-30%). The 135-kDa enzyme, named exo-β-D-glucosaminidase, released a single GlcN residue from the GlcN oligomers and chitosan, but did not release GlcNAc residues from either GlcNAc oligomer or colloidal chitin.
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