Tuesday, May 1, 2012: 3:30 PM
Waterbury Ballroom, 2nd fl (Sheraton New Orleans)
The efficiency of enzymatic conversion of recalcitrant biomass remains an important limiting factor in biorefinery development. Recently, it has been shown that proteins currently classified as CBM33 and GH61 cleave recalcitrant polysaccharides via an oxidative mechanism involving molecular oxygen [1]. The activity of these enzymes, which seem to comprise a new type of copper oxidases, was first discovered for a CBM33 acting on chitin [1,2], followed by the discovery of cellulose-active CBM33s [3]. These studies were followed up by several studies showing that structurally homologous fungal GH61 proteins use a similar mechanism for the degradation of cellulose [4-6]. The CBM33 and GH61 enzymes are unique in that they bind to surfaces rather than to single polysaccharide chains, thus boosting the activity of classical hydrolytic enzymes that depend on gaining access to single (“de-crystallized”) polysaccharide chains and chain ends [1]. These novel enzymes are abundant in biomass-converting microorganisms and open novel avenues in the enzymatic saccharification of cellulose and biomass in general. Interestingly, recent studies on the microbiomes of herbivores indicate that there may exist several other enzymes and enzyme systems for biomass conversion that are worth further exploration [7].
1) Vaaje-Kolstad G. et al., 2011, Science, 330:219-222.
2) Vaaje-Kolstad, G. et al., 2005, JBC, 280:28492-28497.
3) Forsberg, Z. et al., Protein Science, 2011, 20:1479-1483.
4) Quinlan, R. J. et al., PNAS, 2011, 108:15079-15084.
5) Westereng, B. et al., PLoS One. 2011;6(11):e27807.
6) Phillips, C.M. et al., ACS Chemical Biology, in press.
7) Pope, P.B. et al., submitted for publication.