Hyperthermostable acetyl xylan esterase.
Bottom Line: Thermotoga maritima AxeA represents the most thermostable acetyl xylan esterase known to date.Differential scanning calorimetry analysis of the thermal stability of AxeA corroborated its extreme heat resistance.A multi-phasic unfolding behaviour was found, with two apparent exothermic peaks at approximately 100-104 °C and 107.5 °C.
Affiliation: Institut f. Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, D-37077 Goettingen, Germany.Show MeSH
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Mentions: Using a 10 min assay in 100 mM sodium phosphate buffer at pH 5.5 and chemically acetylated xylan as the substrate (for each temperature a control reaction without enzyme was necessary to account for non‐enzymatic deacetylation; see Experimental procedures for details), the maximum activity of AxeA was measured at 90°C (Fig. 3). The influence of increasing temperature on AxeA inactivation, which was determined by incubation of pure AxeA at a concentration of 330 µg ml−1 in 50 mM sodium phosphate buffer pH 6.5 in the absence of substrate at various temperatures, withdrawing aliquots and measuring the residual activity with the pNP‐acetate standard assay, is depicted in Fig. 4.
Affiliation: Institut f. Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, D-37077 Goettingen, Germany.