Mode of action of endo-beta-1,4-xylanases of families 10 and 11 on acidic xylooligosaccharides.
Mode of action of endo-beta-1,4-xylanases (EXs) of glycoside hydrolase families 10 (GH-10) and 11 (GH-11) was examined on various acidic xylooligosaccharides. As expected, none of the enzymes of GH-10 cleaved aldotetraouronic acid (MeGlcA3Xyl3), which is the shortest acidic product of the action of these EXs on glucuronoxylan. Surprisingly, aldopentaouronic acid (MeGlcA3Xyl4) was also not attacked. Only aldohexaouronic acid (MeGlcA3Xyl5) served as a substrate and was cleaved to xylobiose and aldotetraouronic acid. These results suggested that binding of xylopyranosyl residue in the -2 subsite is prerequisite for cleavage of the linkage adjacent to the xylopyranosyl unit carrying MeGlcA. EXs of family GH-11 cleaved neither aldotetraouronic acid, nor aldopentaouronic acid, which is in agreement with their action on glucuronoxylan. Aldohexaouronic acid was cleaved to aldopentaouronic acid and xylobiose without any production of xylose, suggesting that a xylosyl transfer reaction is involved in the degradation of the substrate by EXs of GH-11.
Kolenová
Katarína
K
Slovak Academy of Sciences, Institute of Chemistry, Dúbravská cesta 9, 84538 Bratislava, Slovakia. chemptk@savba.sk
Vrsanská
Mária
M
Biely
Peter
P
D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007526:Isoelectric Point; D008970:Molecular Weight; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D014995:Xylosidases / Q000737:chemistry / Q000378:metabolism*
D009844:Oligosaccharides; D014995:Xylosidases; D043364:Endo-1,4-beta Xylanases