Abstract
Two alpha-L-rhamnohydrolases with different substrate specificities were isolated from a commercial preparation produced by Aspergillus aculeatus. The first rhamnohydrolase was active toward p-nitrophenyl-alpha-L- rhamnopyranoside, naringin, and hesperidin and was termed p-nitrophenyl-alpha-L-rhamnopyranohydrolase (pnp-rhamnohydrolase). From the data collected, the enzyme seemed specific for the alpha-1,2- or alpha-1,6-linkage to beta-D-glucose. The pnp-rhamnohydrolase had a molecular mass of 87 kD (sodium dodecyl sulfate-polyacrylamide gel electrophoresis), a pH optimum of 5.5 to 6, a temperature optimum of 60 degrees C, and a specific activity toward pnp-alpha-L-rhamnopyranoside (pnp-Rha) of 13 units mg-1 protein. The second rhamnohydrolase, on the contrary, was active toward rhamnogalacturonan (RG) fragments, releasing Rha, and was therefore termed RG-rhamnohydrolase. The RG-rhamnohydrolase had a molecular mass of 84 kD, a pH optimum of 4, a temperature optimum of 60 degrees C, and a specific activity toward RG oligomers of 60 units mg-1 protein. The RG-rhamnohydrolase liberated Rha from the nonreducing end of the RG chain and appeared specific for the alpha-1,4-linkage to alpha-D-galacturonic acid. The enzyme was hindered when this terminal Rha residue was substituted at the 4-position by a beta-D-galactose. The results so far obtained did not indicate particular preference of the enzyme for low or high molecular mass RG fragments. From the results it can be concluded that a new enzyme, an RG alpha-L-rhamnopyranohydrolase, has been isolated with high specificity toward RG regions of pectin.
Full Text
The Full Text of this article is available as a PDF (1.5 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- BARRETT A. J., NORTHCOTE D. H. APPLE FRUIT PECTIC SUBSTANCES. Biochem J. 1965 Mar;94:617–627. doi: 10.1042/bj0940617. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Colquhoun I. J., de Ruiter G. A., Schols H. A., Voragen A. G. Identification by n.m.r. spectroscopy of oligosaccharides obtained by treatment of the hairy regions of apple pectin with rhamnogalacturonase. Carbohydr Res. 1990 Sep 30;206(1):131–144. doi: 10.1016/0008-6215(90)84012-j. [DOI] [PubMed] [Google Scholar]
- De Ruiter G. A., Schols H. A., Voragen A. G., Rombouts F. M. Carbohydrate analysis of water-soluble uronic acid-containing polysaccharides with high-performance anion-exchange chromatography using methanolysis combined with TFA hydrolysis is superior to four other methods. Anal Biochem. 1992 Nov 15;207(1):176–185. doi: 10.1016/0003-2697(92)90520-h. [DOI] [PubMed] [Google Scholar]
- Labavitch J. M., Freeman L. E., Albersheim P. Structure of plant cell walls. Purification and characterization of a beta-1,4-galactanase which degrades a structural component of the primary cell walls of dicots. J Biol Chem. 1976 Oct 10;251(19):5904–5910. [PubMed] [Google Scholar]
- Lee Y. C. High-performance anion-exchange chromatography for carbohydrate analysis. Anal Biochem. 1990 Sep;189(2):151–162. doi: 10.1016/0003-2697(90)90099-u. [DOI] [PubMed] [Google Scholar]
- Powell D. A., Morris E. R., Gidley M. J., Rees D. A. Conformations and interactions of pectins. II. Influences of residue sequence on chain association in calcium pectate gels. J Mol Biol. 1982 Mar 15;155(4):517–531. doi: 10.1016/0022-2836(82)90485-5. [DOI] [PubMed] [Google Scholar]
- Puvanesarajah V., Darvill A. G., Albersheim P. Structural characterization of two oligosaccharide fragments formed by the selective cleavage of rhamnogalacturonan II: evidence for the anomeric configuration and attachment sites of apiose and 3-deoxy-2-heptulosaric acid. Carbohydr Res. 1991 Sep 30;218:211–222. doi: 10.1016/0008-6215(91)84099-z. [DOI] [PubMed] [Google Scholar]
- Schols H. A., Voragen A. G., Colquhoun I. J. Isolation and characterization of rhamnogalacturonan oligomers, liberated during degradation of pectic hairy regions by rhamnogalacturonase. Carbohydr Res. 1994 Mar 18;256(1):97–111. doi: 10.1016/0008-6215(94)84230-2. [DOI] [PubMed] [Google Scholar]