Purification and characterization of a chitinase from Aeromonas media CZW001 as a biocatalyst for producing chitinpentaose and chitinhexaose.

Developing chitinase suitable for the bioconversion of chitin to chitin oligosaccharides has attracted significant attention due to its benefits in environmental protection. In this study, chitinase from Aeromonas media CZW001 (AmChi) was purified and characterized. The molecular weight of AmChi was approximately 40 kDa. AmChi exhibited maximum catalytic activity at pH 8.0 with an optimum temperature of 55°C and showed broad stability between 15 and 65°C and between pH 5.0 and 9.0. AmChi was activated by Mg2+ , Na+ , and K+ and inhibited by Hg+ , Co2+ , Fe2+ , Ca2+ , Ag+ , Zn2+ , and EDTA. The main products of AmChi on colloidal chitin were chitinhexaose and chitinpentaose. AmChi had better substrate specificity for powdered chitin than colloidal chitin and had a higher catalytic efficiency toward (GlcNAc)5 than colloidal chitin. AmChi inhibited fungal growth in a dose-dependent manner. These results suggest that AmChi could be used for the enzymatic degradation of chitin to produce chitinhexaose and chitinpentaose, which have several industrial applications.

A Novel Potent Crystalline Chitin Decomposer: Chitin Deacetylase from Acinetobacter schindleri MCDA01.

Chitosan is a functional ingredient that is widely used in food chemistry as an emulsifier, flocculant, antioxidant, or preservative. Chitin deacetylases (CDAs) can catalyze the hydrolysis of acetyl groups, making them useful in the clean production of chitosan. However, the high inactivity of crystalline chitin catalyzed by CDAs has been regarded as the technical bottleneck of crystalline chitin deacetylation. Here, we mined the AsCDA gene from the genome of Acinetobacter schindleri MCDA01 and identified a member of the uraD_N-term-dom superfamily, which was a novel chitin deacetylase with the highest deacetylation activity. The AsCDA gene was expressed in Escherichia coli BL21 by IPTG induction, whose activity to colloidal chitin, α-chitin, and ß-chitin reached 478.96 U/mg, 397.07 U/mg, and 133.27 U/mg, respectively. In 12 h, the enzymatic hydrolysis of AsCDA removed 63.05% of the acetyl groups from α-chitin to prepare industrial chitosan with a degree of deacetylation higher than 85%. AsCDA, as a potent chitin decomposer in the production of chitosan, plays a positive role in the upgrading of the chitosan industry and the value-added utilization of chitin biological resources.

Discovery of Chitin Deacetylase Inhibitors through Structure-Based Virtual Screening and Biological Assays.

Chitin deacetylase (CDA) inhibitors were developed as novel antifungal agents because CDA participates in critical fungal physiological and metabolic processes and increases virulence in soilborne fungal pathogens. However, few CDA inhibitors have been reported. In this study, 150 candidate CDA inhibitors were selected from the commercial Chemdiv compound library through structure-based virtual screening. The top-ranked 25 compounds were further evaluated for biological activity. The compound J075-4187 had an IC50 of 4.24 ± 0.16 µM for AnCDA. Molecular docking calculations predicted that compound J075-4187 binds to the amino acid residues, including active sites (H101, D48). Furthermore, compound J075-4187 inhibited food spoilage fungi and plant pathogenic fungi, with minimum inhibitory concentration (MIC) at 260 µg/ml and minimum fungicidal concentration (MFC) at 520 µg/ml. Therefore, compound J075-4187 is a good candidate for use in developing antifungal agents for fungi control.

Association between p73 G4C14-to-A4T14 polymorphism and lung cancer risk: A systematic review and meta-analysis.

OBJECTIVE: This study was conducted to evaluate the relationship between the p73 G4C14-to-A4T14 polymorphism (hereafter, G4C14-to-A4T14) and lung cancer risk. METHODS: The studies on the relationship between G4C14-A4T14 and lung cancer risk published as of November 5, 2018, were comprehensively searched in PubMed, Embase, the Cochrane Library, the Chinese Wanfang database, China National Knowledge Infrastructure (CNKI), and China Biology Medicine (CBM). The last update was on May 24, 2019. Statistical analysis was performed using Stata 12.0. RESULTS: The association between G4C14-A4T14 and lung cancer risk was analyzed in nine studies. The findings indicate no association between G4C14-to-A4T14 and lung cancer risk (allele model: OR = 0.90, 95% CI: 0.73-1.11, I2  = 86.0%, P = .330; dominant model: OR = 0.93, 95% CI: 0.74-1.17, I2  = 82.6%, P = .551; recessive model: OR = 0.75, 95% CI: 0.50-1.13, I2  = 75.2%, P = .165; homozygote model: OR = 0.74, 95% CI: 0.47-1.17, I2  = 79.6%, P = .199; heterozygote model: OR = 0.98, 95% CI: 0.80-1.21, I2  = 75.8%, P = .879). The heterogeneity between subgroups by cancer types and genotyping method was significantly reduced. After the deletion of suspected duplicates, no association was found between G4C14-to-A4T14 and lung cancer susceptibility. CONCLUSION: Our meta-analysis confirms that G4C14-to-A4T14 is not significantly related to lung cancer risk.