Reaction: Hydrolysis of terminal, non-reducing (2→6)-linked β-D-fructofuranose residues in fructans
For diagram click here.
Other name(s): β-(2-6)-fructan exohydrolase; levanase; 6-FEH; β-(2,6)-D-fructan fructohydrolase
Systematic name: (2→6)-β-D-fructan fructohydrolase
Comments: Possesses one of the activities of EC 3.2.1.80, fructan β-fructosidase. While the best substrates are the levan-type fructans such as 6-kestotriose [β-D-fructofuranosyl-(2→6)-β-D-fructofuranosyl α-D-glucopyranoside] and 6,6-kestotetraose [β-D-fructofuranosyl-(2→6)-β-D-fructofuranosyl-(2→6)-β-D-fructofuranosyl α-D-glucopyranoside], some (but not all) inulin-type fructans can also be hydrolysed, but more slowly [cf. EC 3.2.1.153, fructan β-(2,1)-fructosidase). Sucrose, while being a very poor substrate, can substantially inhibit enzyme activity in some cases.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 1000597-62-5
References:
1. Marx, S.P., Nösberger, J. and Frehner, M. Hydrolysis of fructan in grasses: A β-(2-6)-linkage specific fructan-β-fructosidase from stubble of Lolium perenne. New Phytol. 135 (1997) 279-290.
2. Van den Ende, W., De Coninck, B., Clerens, S., Vergauwen, R. and Van Laere, A. Unexpected presence of fructan 6-exohydrolases (6-FEHs) in non-fructan plants: characterization, cloning, mass mapping and functional analysis of a novel 'cell-wall invertase-like' specific 6-FEH from sugar beet (Beta vulgaris L.). Plant J. 36 (2003) 697-710. [PMID: 14617070]
3. Henson, C.A. and Livingston, D.P., III. Purification and characterization of an oat fructan exohydrolase that preferentially hydrolyzes β-2,6-fructans. Plant Physiol. 110 (1996) 639-644.