In Silico Comparison of the Hemicelluloses Xyloglucan and Glucuronoarabinoxylan in Protecting Cellulose from Degradation

Computation

Graeme T. Attwood¹  Christina D. Moon¹  William J. Kelly¹  Indrakumar Vetharaniam²  Martin Upsdell²  Philip J. Harris³ 

[1] AgResearch Limited, Grasslands Research Centre, Private Bag 11008, Palmerston North 4442,New Zealand;AgResearch Limited, Ruakura Research Centre, Private Bag 3123, Hamilton 3240, New Zealand;School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand;

关键词: plant cell wall;    lignocellulose;    enzymatic degradation;    enzymes;    accessibility;    competitive inhibition;    rumen;    second-generation biofuels, agent-based modelling;    simulation model;   

DOI  :  10.3390/computation3030336

来源: DOAJ

【 摘 要 】

We used a previously developed simulation model of a plant cell walland its enzymatic degradation to compare the abilities of two hemicelluloses, glucuronoarabinoxylan (GAX) and xyloglucan (XG), to protect cellulose microfibrils (CMFs) from attack by cellulose-degrading enzymes. Additionally, we investigated the effect of XG abundance on the degradation rate of CMFs in the presence of the same enzymes. Simulations were run using hypothetical cell-wall compositions in which the numbers and arrangement of CMFs and (1,3;1,4)-β-glucan were kept constant, but the proportions of GAX and XG were altered. Scenarios considered walls with low and equal proportions of either GAX or XG, and also low, medium and high proportions of XG in the absence of GAX. The rate of CMF degradation was much lower in walls with GAX than walls with XG, except for early in the simulation when the reverse held, suggesting that XGs were protecting CMFs by competitive inhibition. Increasing XG content reduced both the degradation rate of CMFs and the percent of XG degraded, indicating that activity of enzymes decreased with XG density despite XG being degradable. Glucose oligosaccharide breakdown products were analysed on the basis of the originating polysaccharide and their degree of polymerisation (DP). The presence of GAX as opposed to equal amounts ofXG had some significant effects on the amount and profile of breakdown products from XG and CMFs.

【 授权许可】

Unknown