Figure 8

K _m determination for etheno-NAD⁺ of chicken ART4. Recombinant chART4 (7 μg/ml) was incubated at room temperature for 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 8, 10, 12, 15, 20, and 30 min in the presence of poly-L-arginine (1 mg/ml) and 0.5, 1, 2, and 5 μM etheno-NAD⁺ in the presence (open circles) and absence (filled circles) of PNGase F. The ADP-ribosyltransferase activity was determined by measuring the increase in fluorescence intensity. Shown is a double reciprocal plot of the data of the dose response. Data show one representative experiment out of three (K_m "untreated" vs. K_m "treated" chART4 p = 0.062, Student's t-test).