Table 1.

Summary of studies on ITPA catalytic properties

Reference	Liakopoulou [11]	Vanderheiden, 1970 [12]	Vanderheiden, 1979 [13]	Holmes [14]	Lin [1]	Stepchenkova [18]	Herting [15, 19]
Protein source	Hemolysate	Partially purified from hemolysate	Purified from hemolysate	Hemolysate	Purified from E. coli	Purified from E. coli	Purified from E. coli
Km	1 × 10−4 M	6 × 10−4 M	1.3 × 10−4 M	7 × 10−5 M	5.1 × 10−4 M	4.0 × 10−4 M	3.25 ×10−5 M
Vmax	N/A	N/A	1.2 × 10−9 M/min	N/A	1520 µmol/(min·mg)	N/A	N/A
kcat	N/A	N/A	N/A	N/A	580 s−1	91 s−1	79.6 s−1
pH optimum	7.5	8.5 (9.5 with DTT)	8.6 in Tris-HCl 9.6 in glycine	N/A	10.0	N/A	N/A
Mg2+ optimum	50 mM	50 mM	100 mM	60 mM	30 – 100 mM	N/A	N/A
Substrate inhibition	No	Yes	Slight	No	Yes	Yes	Yes
Reducing agent activation	N/A	Yes	No	Yes	Yes	N/A	N/A

The substrate was ITP in all cases except for Herting, where dITP was used.