Action Pattern of<i>Streptomyces griseus</i>Chitinase on Partially<i>N</i>-Acetylated Chitosan

Ohtakara, Akira; Matsunaga, Hirohide; Mitsutomi, Masaru

doi:10.1080/00021369.1990.10870469

Cited by 12 publications

(20 citation statements)

References 8 publications

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“…5). From (GlcN) 6 , the wild-type chitosanase produced (GlcN) 3 abundantly and (GlcN) 2 and (GlcN) 4 in lesser amounts. The product distribution was not changed even when each of the mutant chitosanases was used instead.…”

Section: Resultsmentioning

confidence: 99%

“…21), highly deacetylated chitosan (d.a. Ͻ0.01), and (GlcN) 6 as substrates are shown in Table II. The relative activities determined by using chitosan as substrate appear to be consistent with those determined by (GlcN) 6 .…”

Section: Resultsmentioning

confidence: 99%

“…Ͻ0.01), and (GlcN) 6 as substrates are shown in Table II. The relative activities determined by using chitosan as substrate appear to be consistent with those determined by (GlcN) 6 . These determinations confirmed what was seen on the plate assay; mutants of residues 6 or 36 had nearly normal chitosanase activity, while mutants of residues 22 or 40 were severely affected in their activity.…”

Section: Resultsmentioning

confidence: 99%

“…Chitohexaose Hydrolysis-The profiles of products generated from (GlcN) 6 were analyzed for mutants in position 37 or 40 (Fig. 5).…”

Section: Resultsmentioning

confidence: 99%

“…Time Course of the Enzymatic Reaction of (GlcN) 6 -The substrate, (GlcN) 6 , was dissolved in 50 mM sodium acetate buffer, pH 5.5, to give 16.6 mM solution. The enzyme (0.14 -0.19 nmol) was added to 0.5 ml of the substrate solution, and the reaction mixture was incubated at 40°C.…”

Section: Agccgcggccctcaccgatgtmentioning

confidence: 99%

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Site-directed Mutagenesis of Evolutionary Conserved Carboxylic Amino Acids in the Chitosanase from Streptomyces sp. N174 Reveals Two Residues Essential for Catalysis

Boucher

Fukamizo

Honda

et al. 1995

Journal of Biological Chemistry

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The comparison of four sequences of prokaryotic chitosanases, belonging to the family 46 of glycosyl hydrolases, revealed a conserved N-terminal module of 50 residues, including five invariant carboxylic residues. To verify if some of these residues are important for catalytic activity in the chitosanase from Streptomyces sp. N174, these 5 residues were replaced by site-directed mutagenesis. Substitutions of Glu-22 or Asp-40 with sterically conservative (E22Q, D40N) or functionally conservative (E22D, D40E) residues reduced drastically specific activity and k cat , while K m was only slightly changed. The other residues examined, Asp-6, Glu-36, and Asp-37, retained significant activity after mutation. Circular dichroism studies of the mutant chitosanases confirmed that the observed effects are not due to changes in secondary structure. These results suggested that Glu-22 and Asp-40 are directly involved in the catalytic center of the chitosanase and the other residues are not essential for catalytic activity.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Chitohexaose Hydrolysis-The profiles of products generated from (GlcN) 6 were analyzed for mutants in position 37 or 40 (Fig. 5).…”

Section: Resultsmentioning

confidence: 99%

Section: Agccgcggccctcaccgatgtmentioning

confidence: 99%

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Site-directed Mutagenesis of Evolutionary Conserved Carboxylic Amino Acids in the Chitosanase from Streptomyces sp. N174 Reveals Two Residues Essential for Catalysis

Boucher

Fukamizo

Honda

et al. 1995

Journal of Biological Chemistry

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Enzymatic Polysaccharide Degradation

Munteanu¹,

Ritter²

2010

Biocatalysis in Polymer Chemistry

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Changes in the microstructure and enzymatic hydrolysis performance of chitin treated by steam explosion, high‐pressure homogenization, and γ radiation

Zhai

Zhang

et al. 2020

J of Applied Polymer Sci

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This research intends to reduce the crystallinity of chitin with physical methods so as to improve the enzymatic hydrolysis efficiency of chitin. Scanning electron microscopy showed that both steam explosion and high‐pressure homogenization significantly enlarged the pores in shrimp shells, which are made up of chitin, but γ radiation did not. X‐ray diffraction showed that the crystallinity index of chitin decreased by 23.2% in the (110) plane and 24.7% in the (020) plane after three rounds of steam explosion and decreased by 12.4% in the (110) plane and 28.7% in the (020) plane after three rounds of high‐pressure homogenization. After γ radiation, however, there was no significant change. The corresponding deacetylation degrees of the chitin treated with steam explosion and high‐pressure homogenization increased by 13.2 and 5.7%, respectively. The natural, steam‐exploded and high‐pressure homogenized chitins respectively produced 0.251, 0.145, and 0.407 mg/ml reducing sugars with the hydrolysis of Streptomyces griseus chitinase. However, when hydrolyzed by Paenibacillus sp. A1 chitinase the steam‐exploded and the high‐pressure homogenized chitin respectively released 40 and 300% more reducing sugars than the natural chitin. The results found that steam explosion and high‐pressure homogenization can reduce the crystallinity of chitin, and make it prone to enzymatic hydrolysis.

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Action Pattern ofStreptomyces griseusChitinase on PartiallyN-Acetylated Chitosan

Cited by 12 publications

References 8 publications

Site-directed Mutagenesis of Evolutionary Conserved Carboxylic Amino Acids in the Chitosanase from Streptomyces sp. N174 Reveals Two Residues Essential for Catalysis

Site-directed Mutagenesis of Evolutionary Conserved Carboxylic Amino Acids in the Chitosanase from Streptomyces sp. N174 Reveals Two Residues Essential for Catalysis

Enzymatic Polysaccharide Degradation

Changes in the microstructure and enzymatic hydrolysis performance of chitin treated by steam explosion, high‐pressure homogenization, and γ radiation

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