Abstract
A xylanase, which produces exclusively xylobiose from oat spelt and birch xylans, was isolated from the culture medium of Aeromonas caviae ME-1. The enzyme (xylanase V) was purified by ammonium sulfate fractionation, hydrophobic interaction, and ion-exchange and gel filtration chromatographies. The homogeneity of the final preparation was demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and agarose gel electrofocusing. The molecular mass and isoelectric point of the xylanase were 46 kDa and 5.4, respectively. Xylanase V had a maximum activity at a pH of 6.8 and at a temperature between 30 and 37°C. It was relatively stable at a pH between 5.0 and 8.6 and a temperature between 25 and 37°C. When soluble birch xylan was used as the substrate, the enzyme had a Km and Vmax of 2 mg/ml and 182 μmol of xylose equivalent liberated · min-1 · mg of protein-1, respectively. By the action of xylanase V on xylans (from oat spelt and birch), only one product corresponding to xylobiose was observed by thin-layer chromatography. The xylanase V putative product was confirmed to be xylobiose by acid and enzymatic hydrolyses. The xylanase had neither β-xylosidase, α-l-arabinofuranosidase, cellulase, nor β-1,3-xylanase activities. Xylotriose was the shortest substrate which the enzyme could attack. These findings suggest that xylanase V is a novel enzyme that cleaves a xylobiose unit from one of the ends of xylans, probably by an exomechanism.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Dekker R. F., Richards G. N. Purification, properties, and mode of action of hemicellulase I produced by Ceratocystis paradoxa. Carbohydr Res. 1975 Jan;39(1):97–114. doi: 10.1016/s0008-6215(00)82642-7. [DOI] [PubMed] [Google Scholar]
- Huang L., Hseu T. H., Wey T. T. Purification and characterization of an endoxylanase from Trichoderma koningii G-39. Biochem J. 1991 Sep 1;278(Pt 2):329–333. doi: 10.1042/bj2780329. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- Reilly P. J. Xylanases: structure and function. Basic Life Sci. 1981;18:111–129. doi: 10.1007/978-1-4684-3980-9_8. [DOI] [PubMed] [Google Scholar]
- Robyt J. F., Ackerman R. J. Isolation, purification, and characterization of a maltotetraose-producing amylase from Pseudomonas stutzeri. Arch Biochem Biophys. 1971 Jul;145(1):105–114. doi: 10.1016/0003-9861(71)90015-4. [DOI] [PubMed] [Google Scholar]