Fig. 5.
Recovered inosine hydrolase (a) and xanthosine hydrolase (b) activity of Arabidopsis thaliana nucleoside hydrolase (urh) mutant extracts. URH, black bars; urh1 + urh2, gray bars. Soluble root extracts from urh1 and urh2 mutants were mixed and preincubated for 1 h with substrate (−, no substrate; Ino, inosine; Xan, xanthosine) at the respective KM (Michaelis constant) concentration. Substrates were removed by desalting on spin columns using Sephadex G-25 fine before activity measurement. Data show mean ± SD (n = 2–3). Significant differences (P < 0.05) between mutant mix (urh1 + urh2) and wild-type (URH), as determined using unpaired two-tailed t-tests, are marked with an asterisk.