Extraction of CBH from transgenic corn stover leaf into tap water after mild disruption. Transgenic corn stover leaf containing recombinant CBH was disrupted with three (white squares), six (grey squares), or nine (black squares) passes through a cutting mill. Three water extracts were prepared for each level of tissue disruption. Water extracts were also prepared from corn stover leaf milled to a particle size of <2 mm and disrupted using a bead mill (dotted line). CBH activity was measured in the extracts by monitoring the ability of extracts to release 4-methylumbelliferone (4-Mu) from 4-methylumbelliferyl-β-D-lactopyranoside (MUL) at pH 4.75 and 40°C, relative to a 4-Mu standard curve. Activity is presented as micromoles 4-Mu released per min per mg of protein. All samples were analysed in triplicate, and error bars represent standard deviation.