Identifying reaction modules in metabolic pathways: bioinformatic deduction and experimental validation of a new putative route in purine catabolism

Table 3 Characterization of the Rubrobacter xylanophilus UGTCase activity

Reaction mixture composition	Assay temperature	Specific activity^c(μmol min^-1 mg^-1)
25 mM potassium arsenate pH 6.8, 20 mM allantoate	37°C	0.046 ± 0.007 ^a
25 mM Hepes pH 6.8, 20 mM allantoate	37°C	n.d. ^a
50 mM potassium phosphate pH 6.8, 20 mM allantoate, 5 mM ornithine, EcOTCase (100 units)	37°C	0.050 ± 0.002 ^b
25 mM Hepes pH 6.8, 20 mM allantoate, 5 mM ornithine, EcOTCase (100 units)	37°C	n.d. ^b
50 mM potassium phosphate pH 6.8, 5 mM ornithine, EcOTCase (100 units)	37°C	n.d. ^b
50 mM potassium phosphate pH 6.8, 20 mM allantoate, 5 mM ornithine, EcOTCase (100 units)	60°C	5.913 ± 0.584 ^b
50 mM potassium phosphate pH 6.8, 5 mM ornithine, EcOTCase (100 units)	60°C	n.d. ^b

^aassessed by quantifying ureidoglycine.
^bassessed by quantifying citrulline.
^cData are the mean ± SD from at least three independent experiments. n.d., not detectable as defined in Methods.

ISSN: 1752-0509