Ståhlberg, J., Johansson, G., and Pettersson, G. Rahkamo, L., Siika-aho, M., Vehviläinen, M., Dolk, M., Viikari, L., Nousianen, P., and Buchert, J. (1951), Chemistry of Wood, Academic Press, New York. Stenberg, K., Tengborg, C., Galbe, M., and Zacchi, G. Imai, T., Boisset, C., Samejima, M., Igarashi, K., and Sugiyama, J. T., Koivula, A., Linder, M., Wohlfahrt, G., Divne, C., and Jones, T. Thesis, Uppsala University, Uppsala, Sweden. Stenberg, K., Tengborg, C., Galbe, M., Zacchi, G., Palmqvist, E., and Hahn-Hägerdal, B. J., Sinning, I., Ståhlberg, J., Reinikainen, T., Srisodsuk, M., Teeri, T., and Jones, T. Kleywegt, G., Zou, J.-Y., Divne, C., Davies, G. 12, 28–33.ĭivne, C., Ståhlberg, J., Reinikainen, T., Ruohonen, L., Pettersson, G., Knowles, J. Saloheimo, M., Nakari-Setälä, T., Tenkanen, M., and Penttilä, M. Holtzapple, M., Cognata, M., Shu, Y., and Hendrickson, C.
Mooney, C., Mansfield, S., Touhy, M., and Saddler, J. Väljamäe, P., Sild, V., Pettersson, G., and Johansson, G. The improved model is supported by adsorption studies during hydrolysis.Įklund, R., Galbe, M., and Zacchi, G. Obstacles created by disordered cellulose chains can be removed by the endo activity of Cel7B, which explains some of the observed synergism between Cel7A and Cel7B. It appears that the processive action of Cel7A becomes hindered by obstacles in the lignocellulose substrate. An improved model is proposed that extends the standard endo-exo synergy model and explains the rapid decrease in hydrolysis rate. The strongest increase in hydrolysis rate was achieved by adding Cel7B. This suggests that enzymes become inactivated while adsorbed to the substrate and that unproductive binding is the main cause of hydrolysis rate reduction. Adding fresh substrate to substrate previously hydrolyzed for 24 h with Cel7A slightly increased the hydrolysis of SPS however, the rate increased even more by adding fresh Cel7A. Thermal instability of the enzymes and product inhibition was not the main cause of reduced hydrolysis rates. Cel7A and Cel7B cooperate synergistically, and synergism was approximately constant during the SPS hydrolysis.
Both enzymes adsorbed rapidly to the substrate during hydrolysis. The hydrolysis rate for both enzymes decreases rapidly with hydrolysis time. Throughout the 48-h hydrolysis, soluble products, hydrolysis rates, and enzyme adsorption to the substrate were measured. Hydrolysis of steam-pretreated spruce (SPS) was performed with Cel7A and Cel7B alone, and in reconstituted mixtures. In this work the mechanism behind the rate reduction was investigated using two dominant cellulases of Trichoderma reesei: exoglucanase Cel7A (formerly known as CBHI) and endoglucanase Cel7B (formerly EGI). It is commonly observed that the rate of enzymatic hydrolysis of solid cellulose substrates declines markedly with time.