Xylose competition assay of Saccharophagus degradans cellobiose phosphorylase activity. The catalytic properties of SdCBP were determined in the presence of 0, 2.5 and 5 mM of xylose. (A) Initial rates of cellobiose phosphorolysis were calculated from the amount of continuous G1P production at different cellobiose concentrations. All reactions were carried out in duplicate. (B) Apparent kinetic parameters of SdCBP supplemented with 0, 2.5 and 5 mM of xylose determined by non-linear curve fitting.