Enzyme kinetics and identification of the rate-limiting step of enzymatic arabinoxylan degradation

Rasmussen, Louise Enggaard; Xu, Cheng; Sørensen, Jens F.; Nielsen, Marie Vejrup; Meyer, Anne S.

doi:10.1016/j.bej.2012.08.004

Cited by 17 publications

(14 citation statements)

References 22 publications

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“…When a glucuronoxylan, such as beechwood xylan, is digested with GH family 11 xylanases, xylotetraose substituted with a 4- o -methylglucuronic acid residue (X4MeGlcA) accumulates as the final reaction product (Biely et al 1997; Kolenová et al 2006). X4MeGlcA generally show resistance against hydrolysis with xylosidase, when substitution by glucuronic acid occurs at X1 of the non-reducing end or the second X1 next to the non-reducing end (Tenkanen et al 1996; Rasmussen et al 2012). Although glucuronic acid is released from short xylooligosaccharides by the actions of α-glucuronidase, X4MeGlcA is too large to be hydrolyzed with the enzyme (Kolenová et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Analysis of functional xylanases in xylan degradation by Aspergillus niger E-1 and characterization of the GH family 10 xylanase XynVII

2013

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Xylanases produced by Aspergillus niger are industrially important and many types of xylanases have been reported. Individual xylanases have been well studied for their enzymatic properties, gene cloning, and heterologous expression. However, less attention has been paid to the relationship between xylanase genes carried on the A. niger genome and xylanases produced by A. niger strains. Therefore, we examined xylanase genes encoded on the genome of A. niger E-1 and xylanases produced in culture. Seven putative xylanase genes, xynI–VII (named in ascending order of the molecular masses of the deduced amino acid sequences), were amplified from the strain E-1 genome using primers designed from the genome sequence of A. niger CBS 513.88 by PCR and phylogenetically classified into three clusters. Additionally, culture supernatant analysis by DE52 anion–exchange column chromatography revealed that this strain produced three xylanases, XynII, XynIII, and XynVII, which were identified by N-terminal amino acid sequencing and MALDI-TOF-MS analyses, in culture when gown in 0.5% xylan medium supplemented with 50 mM succinate. Furthermore, XynVII, the only GH family 10 xylanase in A. niger E-1, was purified and characterized. The purified enzyme showed a single band with a molecular mass of 35 kDa by SDS-PAGE. The highest activity of purified XynVII was observed at 55°C and pH 5.5. The enzyme was stable in the broad pH range of 3–10 and up to 60°C and was resistant to most metal ions and modifying regents. XynVII showed high specificity against beechwood xylan with Km and Vmax values of 2.8 mg mL–1 and 127 μmol min–1mg–1, respectively. TLC and MALDI-TOF-MS analyses showed that the final hydrolyzed products of the enzyme from beechwood xylan were xylose, xylobiose, and xylotriose substituted with a 4-o-metylglucuronic acid residue.

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Section: Discussionmentioning

confidence: 99%

Analysis of functional xylanases in xylan degradation by Aspergillus niger E-1 and characterization of the GH family 10 xylanase XynVII

2013

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“…Therefore, 0.5 g/L was treated as the optimum CA concentration in [Bmim][Tf 2 N], and further experiments on concentration of substrate were carried out at various lipase concentration levels. (20,40,60, 80, 100 and 120 g/L) and CA concentrations (0.15, 0.25, 0.5, 1, 1.5 and 2 g/L) were used under the two different incubation conditions. Fig.…”

Section: The Effect Of Substrate Concentrationmentioning

confidence: 99%

“…The enzymatic kinetics in batch reaction systems were determined using the Michaelis-Menten model [40], and the experimental data were fitted to the Lineweaver-Burk equation (Eq. (7)):…”

Section: Kinetic Constants Analysismentioning

confidence: 99%

Ultrasound irradiation accelerates the lipase-catalyzed synthesis of methyl caffeate in an ionic liquid

Wang

et al. 2015

Journal of Molecular Catalysis B: Enzymatic

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“…This cross‐linking gives grain cell walls their structural properties [26] and the degree of cross‐linking is reflected in the ratio of ferulic acid dimers to xylose [20, 27, 30]. Cross‐linking determines the ease of access of a suite of catalytic enzymes required for complete arabinoxylan digestion [31–33], and therefore the degree of resistance to cell wall degrading enzymes from grain pathogens, or colonic micro‐organisms (fermentation). Bran ( i.e ., the aleurone and outer layers of the grain) is the chief source of grain arabinoxylan [20].…”

Section: Anatomy Of Whole Grains (Wheat As the Example)mentioning

confidence: 99%

Whole grains, type 2 diabetes, coronary heart disease, and hypertension: Links to the aleurone preferred over indigestible fiber

et al. 2013

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Higher whole grain cereal intakes are associated with substantially lower risks of type 2 diabetes, coronary heart disease, and hypertension. These reduced risks have been established in large prospective studies that now include millions of person-years of follow-up. We analyze the results of 11 major prospective studies to provide recommendations about whole grain consumption. The following review establishes the amount of whole grains that should ideally be consumed based on prospective evidence; defines the nature of whole grains; identifies that the whole grain evidence is robust and not due to confounding; and provides a detailed assessment of several potential mechanisms for the effect of whole grains on health. We draw the following conclusions. Firstly, to maintain health, 40 grams or more of whole grains should be consumed daily. This is about a bowl of whole grain breakfast cereal daily, but 80% of the population does not achieve this. Secondly, aleurone in bran is a critical grain component generally overlooked in favor of indigestible fiber. Live aleurone cells constitute 50% of millers’ bran. They store minerals, protein, and the antioxidant ferulic acid, and are clearly more than just indigestible fiber. Finally, we suggest potential roles for magnesium, zinc, and ferulic acid in the development of chronic disease. If the results of prospective studies were applied to the life-style practices of modern societies there exists the potential for enormous personal health and public financial benefits.

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Enzyme kinetics and identification of the rate-limiting step of enzymatic arabinoxylan degradation

Cited by 17 publications

References 22 publications

Analysis of functional xylanases in xylan degradation by Aspergillus niger E-1 and characterization of the GH family 10 xylanase XynVII

Analysis of functional xylanases in xylan degradation by Aspergillus niger E-1 and characterization of the GH family 10 xylanase XynVII

Ultrasound irradiation accelerates the lipase-catalyzed synthesis of methyl caffeate in an ionic liquid

Whole grains, type 2 diabetes, coronary heart disease, and hypertension: Links to the aleurone preferred over indigestible fiber

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