The catalytic rate constant of Trichoderma longibrachiatum family 7 cellobiohydrolase on cellulose

Abstract

Cellobiohydrolases are considered workhorse cellulases in the saccharification of cellulosic substrates. As solubilized cellobiose products are easily measured, cellobiohydrolases have been useful tools in studies of cellulose hydrolysis. Access to purified cellobiohydrolases with known catalytic rate constant (kcat), or the turnover rate, is particularly useful. Here, we determined the kcat of the commercially available Trichoderma longibrachiatum CBHI at 30{degrees}C, 40{degrees}C, and 50{degrees}C to be 0.5 s-1, and 2.6 s-1, and 5.3 s-1, respectively. The energy of activation of productively bound TlCBHI was estimated to be 93 {+/-} 17 kJ/mol.