1 Department of Chemistry, Faculty of Science, Aarhus University, Aarhus University2 Department of Chemistry, Science and Technology, Aarhus University3 Department of Chemistry, Science and Technology, Aarhus University
During the last decades a considerable amount of interest has focused on transformation of cellulosic biomass to renewable energy sources such as ethanol.1,2 Cellulases, secreted by different microorganisms, are key enzymes in this process. However, the degradation of cellulose is a difficult task since cellulose exists in different morphologies that can only be degraded efficiently by a battery of enzymes working together.3 One of the most efficient cellulosic systems is secreted by the fungus Hypocrea jecorina, which also has been employed in the industrial production of ethanol. However, a commonly encountered problem during this process is the "dying off" of enzymes over time,4 possibly caused by one component in the mixture becoming rate-limiting. Currently, no methodologies exists that can accurately profile, identify and quantify active enzymes in a complex mixture and such a methodology is needed. In order to develop suitable reagents to specifically identify and quantify individual cellulases in a mixture it is necessary to construct specific substrates for assay of each enzyme individually. Although all cellulases catalyze the cleavage of b-1,4-glycosidic bonds, it is likely that they exhibit different substrate specificities. Therefore, a small library of derivatives of 2,4-dinitrophenyl cellobioside (2,4-DNPC) and 3,4-dinitrophenyl cellobioside (3,4-DNPC) was prepared. These derivatives contained a series of substituents (X and Y) located at the O4' and O6' position. Inspection of the three-dimensional (X-ray) structures of different cellulases indicated that modifications at other positions would occlude binding, while, typically some space is available around the 4' and 6' position. The substituents were chosen so that further modifications would be possible either by click chemistry or by amine coupling. The kinetic parameters of the library of compounds are to be determined.
Cellulosic biomass, cellulases
Main Research Area:
The 25th International Carbohydrate Symposium (ICS2010), 2010