Spectrophotometry of yCD activity. In (A), are reported the values of de novo formed 5-FU (mM) obtained in presence of yCD (0.5 μg ml-1) and 5-FC (0.18 mM) during the first 9 min of the reaction. In (B) and (C) are reported the 5-FU values obtained with identical reagents but in presence of 2 μg ml-1 of the specific (scFvH5) or irrelevant (scFvGO) antibodies. Slope of lines represents starting speed of the reaction. Correlation coefficient (R) indicates the strength and direction of the linear relationship between time and formed 5-FU.