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Antifungal Activity of Seaweeds and their Extracts
Published in Leonel Pereira, Therapeutic and Nutritional Uses of Algae, 2018
This fungus is a plant pathogen infecting pineapples. P. funiculosum occurs in tropical areas as well as temperate ones. It is also used as a source of the enzymes xylanase and beta-glucanase, which are a nonstarch polysaccharide hydrolyzing enzymes. In culture, it presents white-colored colonies, sometimes of a pale green-grey, slightly slimy and shiny with erected funiculi at the center, filamentous and lighter towards the edges (Pitt and Hocking 1999).
Contact Urticaria, Dermatitis, and Respiratory Allergy Caused by Enzymes
Published in Ana M. Giménez-Arnau, Howard I. Maibach, Contact Urticaria Syndrome, 2014
Stanciu Monica, Denis Sasseville
Cellulose, the major constituent of plants, is a polysaccharide consisting of linear chains of repeating glucose molecules. The links between the glucose moieties are slightly different than those found in starch, making cellulose much more resistant to hydrolysis. Except for herbivores, most animals cannot efficiently break down cellulose because they lack ruminating chambers colonized by symbiotic bacteria that produce cellulase. Hemicelluloses are different polysaccharides, often coexisting with cellulose, present in the cell wall of most plants. These glucans, mannans, xylans and xyloglucans are hydrolyzed by various hemicellulases such as xylanase, produced by bacteria and fungi that feed on plant matter. Both cellulase and xylanase have found many industrial applications, notably in laundry detergents and in the processing of wood pulp.
Chemical Modification Of Tryptophan
Published in Roger L. Lundblad, Chemical Reagents for Protein Modification, 2020
There are several other facets of the use of N-bromosuccinimide for the modification of tryptophanyl residue in proteins which should be considered. The use of the reagent at mildly acidic pH has been mentioned above. Not only does increasing pH decrease specificity in terms of reaction with amino acid residues other than tryptophan but there is a decrease in the modification of tryptophan. This is shown by the studies21 on the modification of a glucoamylase from Aspergillus saitoi. As shown in Figure 14 there is a modest decrease in modification as the pH is increased from 4.0 to 6.0 with a dramatic decrease at pH 7.0. At pH values close to neutrality there is the increased possibility of modification of amino residues other than tryptophan. The pH dependence of N-bromosuccinimide tryptophan modification may well reflect local conformational effects rather than intrinsic chemistry. Stopped-flow studies22 of the N-bromosuccinimide modification of tryptophan-62 in lysozyme shows a marked pH dependence with an observed pKa of 6.2 while there is no pH dependence (3.5 to 8.5) for the modification of N-acetyltryptophan ethyl ester. In studies23 on the reaction on Escherichia coli lac repressor protein with N-bromosuccinimide at pH 7.8 (1.0 M Tris), cysteine was modified as readily as tryptophan with lesser modification of methionine and tyrosine (Figure 15). Although the great majority of N-bromosuccinimide modifications of proteins are performed at pH values less than 5.0 to avoid modification of other functional groups, success can be achieved under less acidic conditions. Kumar et al.24 modified tryptophanyl residues in transcarboxylase in 0.25 M potassium phosphate, pH 6.5, containing 0.1 M dithiothreitol and 0.1 mM phenylmethylsulfonyl fluoride. These investigators also demonstrated that the loss of activity upon modification was not a reflection of gross conformational change by examination of the quenching of intrinsic fluorescence and changes in the susceptibility to tryptic cleavage. In general, modification should occur at a 4 to 6 molar excess (with respect to total tryptophan) of N-bromosuccinimide. Under most reaction conditions, the modification of tryptophanyl residues with N-bromosuccinimide is quite rapid. Time-dependent reactions have, however, been observed such as that reported for xylanase.25 Reaction with 2-hydroxy-5-nitrobenzyl bromide was also time dependent under these reaction conditions. The use of N-bromosuccinimide in the study of proteins is summarized in Table 1.
Influences of Aflatoxin B1 on main intestinal bacteria communities and enzyme activities in mice
Published in Toxin Reviews, 2019
Lu He, Yawei Liu, Yanfang Guo, Nenqun Xiao, Zhoujin Tan
The results of the intestinal enzyme activities are shown in Table 1. Compared with the control group, amylase activity in the AFB1 groups increased significantly (p = .000) while there was no obvious differences in the three groups (p > .05), and the amylase activity in the low-dosage group was significantly higher than that in the middle-dosage group (p = .019). The protease activity in the low-dosage group increased significantly compared with the control group (p = .029) and the high-dosage group (p = 0.001). And the activity of protease in the middle-dosage group was higher than that in the high-dosage group (p = .028). The activity of xylanase (p = .005) and cellulase (p = .002) in the high-dosage group increased significantly compared with the control group and cellulase activity was higher than that in the other three groups (p1 = .002, p2 = .038, p3 = .008).
Thermostable xylanase inhibits and disassembles Pseudomonas aeruginosa biofilms
Published in Biofouling, 2018
Jin-Hyung Lee, Yong-Guy Kim, Jintae Lee
Polysaccharides are a major constituent for the production of an EPS matrix. While P. aeruginosa is one of the best studied models for biofilm formation, the identification of specific carbohydrates by EPS degrading enzymes was evasive due to the difficulty in analyzing EPS (Wozniak et al. 2003; Ma et al. 2009; Flemming and Wingender 2010). Alginate is one of the most extensively studied exopolysaccharides, and is involved in the establishment of microcolonies at the beginning of biofilm formation. Pel is essential for the formation of biofilms (called pellicles) at air–liquid interfaces, and Psl is involved in the adhesion to abiotic and biotic surfaces and in the maintenance of biofilm architecture (Flemming and Wingender 2010). A previous report suggests that cellulase may target glucose, but not cellulose, in biofilm formation by P. aeruginosa PA14 (Friedman and Kolter 2004). Another study showed that cellulase may degrade Psl and Pel in P. aeruginosa PAO1 (Ma et al. 2009). Therefore, targeting the carbohydrate(s) of xylanase in xylanase sensitive strains, such as P. aeruginosa, S. aureus, and E. coli, seems to be a promising strategy.
Interactions between host and gut microbiota in domestic pigs: a review
Published in Gut Microbes, 2020
Yadnyavalkya Patil, Ravi Gooneratne, Xiang-Hong Ju
It is well established that lactobacilli supplementation in neonates aids in the early development of stable gut microflora, stimulates the immune system, and prevents diarrhea.52 Recently, it was also reported that by including xylanase in pig diet, the fecal and ileal counts of beneficial lactobacilli could be increased while simultaneously reducing the E. coli counts.75 The GIT microbial community adapts to variations in the host animal’s diet although the host diet also influences the distribution of microbiota within the GIT.76 The gut microbiota is an environmental regulator of fat storage and adiposity77. Bacteroidetes contain fewer genes for enzymes involved in carbohydrate and lipid metabolism, as compared to Firmicutes. Hence, the abundance of Firmicutes is higher is obese animals.77 Thus, reduction in their numbers following the feeding of DF consolidates our understanding of the positive effects that these fibers exhibit in controlling obesity in higher mammals such as the pig and humans. In another study, when pigs were fed ‘low fat and high fiber’ (LF) or ‘high fat and low fiber’ (HF) diets, the gene copy numbers for Lactobacilli spp., Bifidobacterium and Faecalibacterium prausnitzii were observed to be higher in LF-diet-fed pigs, while HF-diet-fed pigs contained more Enterobacteriaceae.78 The LF diet containing higher amounts of DF was able to stimulate the growth of beneficial bacteria in the microbiota and increase the production of SCFAs, especially butyrate. In contrast, the HF diet increased the number of potentially pathogenic organisms. Spurlock and Gabler (2008) presented a review of literature wherein swine were used as a model to study human obesity. Some breeds of swine such as the Ossabaw breed from the United States of America readily become obese in the absence of high-fiber diets.79