A comparative study of two retaining enzymes of Trichoderma reesei: transglycosylation of oligosaccharides catalysed by the cellobiohydrolase I, Cel7A, and the β‐mannanase, Man5A

FEBS Letters

Koivula, Anu³  Helin, Jari²  Harjunpää, Vesa¹  Siika-aho, Matti³ 

[1] VTT Chemical Technology, P.O. Box 1401, FIN-02044 VTT, Espoo, Finland;Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland;VTT Biotechnology and Food Research, P.O. Box 1500, FIN-02044 VTT, Espoo, Finland

关键词: Cellulase;    Mannanase;    Oligosaccharide;    Transglycosylation;    Trichoderma reesei;    HPLC;    high performance liquid chromatography;    MALDI-TOF MS;    matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry;    NMR;    nuclear magnetic resonance;    Cel;    endoglucanase/cellobiohydrolase/cellulase;    Man;    β-mannanase;    Xyn;    xylanase;    Glc1–Glc6;    glucose–cellohexaose;    Man1–Man6;    mannose–mannohexaose;   

DOI  :  10.1016/S0014-5793(98)01692-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

HPLC, MALDI-TOF MS and NMR spectroscopy were used to investigate the hydrolysis of cello- and manno-oligosaccharides by Cel7A and Man5A from Trichoderma reesei. The experimental progress curves were analysed by fitting the numerically integrated kinetic equations, which provided cleavage patterns for oligosaccharides. This data evaluation procedure accounts for product inhibition and avoids the initial slope approximation. In addition, a transglycosylation step had to be included in the model to reproduce the experimental progress curves. For the hydrolysis of manno-oligosaccharides, Man_4–6, by Man5A no mannose was detected at the beginning of the reaction showing that only the internal linkages are hydrolysed. For cellotriose and cellotetraose hydrolysis by Cel7A, the main product is cellobiose and glucose is released from the non-reducing end of the substrate. Intermediary products longer than the substrates were detected by MALDI-TOF MS when oligosaccharides (Glc_4–6 or Man_4–6) were hydrolysed by either Cel7A or Man5A. Interestingly, two distinct transglycosylation pathways could be observed. Cel7A produced intermediates that are one unit longer than the substrate, whereas Man5A produced intermediates that are two units longer than the substrate.

【 授权许可】

Unknown