Specific xyloglucanases as a new class of polysaccharide-degrading enzymes

• Published in: Biochimica et biophysica acta 2004-11, Vol.1674 (3), p.268-281
• Main Authors: Grishutin, Sergey G., Gusakov, Alexander V., Markov, Alexander V., Ustinov, Boris B., Semenova, Margarita V., Sinitsyn, Arkady P.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Aspergillus - enzymology; Aspergillus japonicus; Cellulase - isolation & purification; Cellulase - metabolism; Chrysosporium - enzymology; Chrysosporium lucknowense; Endoglucanase; Glycoside Hydrolases - chemistry; Glycoside Hydrolases - isolation & purification; Glycoside Hydrolases - metabolism; Kinetics; Molecular Sequence Data; Peptide Fragments - chemistry; Polysaccharides - metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Substrate Specificity; Trichoderma reesei; Xyloglucan; Xyloglucanase
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2004.07.001

Three specific xyloglucanases (XGs) were isolated from Aspergillus japonicus (32 kDa, p I 2.8), Chrysosporium lucknowense (78 kDa, p I 3.8) and Trichoderma reesei (75–105 kDa, p I 4.1–4.3). The characteristic feature of these enzymes was their high specific activity toward tamarind xyloglucan, whereas the activity against carboxymethylcellulose (CMC) and barley β-glucan was absent or very low. Peptide mass fingerprinting using MALDI-TOF mass spectrometry showed that the T. reesei XG represents Cel74A, whose gene has been discovered recently (GenBank accession no. AY281371), but the enzyme has not been characterized and described elsewhere. Tryptic peptides from A. japonicus and C. lucknowense xyloglucanases did not show any identity to those from known glycoside hydrolases. All enzymes produced XXXG, XXLG/XLXG and XLLG oligosaccharides as the end products of xyloglucan hydrolysis. A. japonicus XG displayed an endo-type of attack on the polymeric substrate, while the mode of action of two other xyloglucanases was similar to the exo-type, when oligosaccharides containing four glucose residues in the main chain were split off the ends of xyloglucan molecules. These results together with growing literature data allow concluding that specific xyloglucanases may represent a new class of glycoside hydrolases, which are different from regular endo-1,4-β-glucanases.