Characterization of a GH Family 20 Exo-β--acetylhexosaminidase with Antifungal Activity from .

We characterized HEX, which is a glycoside hydrolase (GH) family 20 exo-β--acetylhexosaminidase found in . HEX exolytically hydrolyzed chitin oligosaccharides from their non-reducing ends, and yielded -acetylglucosamine (GlcNAc) as the end product. According to the initial rate of substrate hydrolysis, the rates of (GlcNAc) and (GlcNAc) hydrolysis were greater than the rates for the other oligosaccharides.

Characterization of a novel exo-chitosanase, an exo-chitobiohydrolase, from Gongronella butleri.

An exo-chitosanase was purified from the culture filtrate of Gongronella butleri NBRC105989 to homogeneity by ammonium sulfate precipitation, followed by column chromatography using CM-Sephadex C-50 and Sephadex G-100. The enzyme comprised a monomeric protein with a molecular weight of approximately 47,000 according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme exhibited optimum activity at pH 4.

Classification of chitosanases by hydrolytic specificity toward N¹,N⁴-diacetylchitohexaose.

The hydrolytic specificities of chitosanases were determined using N¹,N⁴-diacetylchitohexaose [(GlcN)₂-GlcNAc-(GlcN)₂-GlcNAc]. The results for the hydrolytic specificities of chitosanases belonging to subclasses I, II, and III toward chitohexaose and N¹,N⁴-diacetylchitohexaose agreed with previous results obtained by analysis of the hydrolysis products of partially N-acetylated chitosan. N¹,N⁴-Diacetylchitohexaose is a useful substrate to determine the hydrolytic specificity of chitosanase.

Characterization of a chitosanase from Aspergillus fumigatus ATCC13073.

Chitosanase II was purified from the culture filtrate of Aspergillus fumigatus ATCC13073. The purified enzyme had a molecular mass of 23.5 kDa.

Direct binding of a plant LysM receptor-like kinase, LysM RLK1/CERK1, to chitin in vitro.

Plants induce immune responses against fungal pathogens by recognition of chitin, which is a component of the fungal cell wall. Recent studies have revealed that LysM receptor-like kinase 1/chitin elicitor receptor kinase 1 (LysM RLK1/CERK1) is a critical component for the immune responses to chitin in Arabidopsis thaliana. However, the molecular mechanism of the chitin recognition by LysM RLK1 still remains unknown.