TABLE 3.

Substrate specificity of rSso0417 PGA mutase^a

Potential substrate	[32P]Pi remaining (% control) at a substrate concn of:
	0.01 mM	0.02 mM	0.04 mM	0.1 mM	1 mM	10 mM
3-PGA	17	17	15	11	9	9
2-PGA	-	-	-	11	9	6
Glyceric acid	-	-	-	69	34	24
β-Glycerolphosphate	51	-	-	37	-	-
Erythrose-4-phosphate	91	78	59	23	-	-
Ribulose-5-phosphate	57	40	29	17	-	-

^aPotential substrates were assayed for their ability to cause the disappearance of bound [³²P]phosphate from the putative PGA mutase. Recombinant Sso0417 PGA mutase was incubated with [γ-³²P]ATP, and the [³²P]phosphorylated protein was isolated by gel filtration chromatography. Portions (5 μg, each containing ∼0.5 mol of P_i/mol) were incubated for 15 min at 65°C in 50 μl of 25 mM MOPS (pH 7.0) containing 5 mM MgCl₂, 5 mM MnCl₂, and one of the potential substrates listed at the indicated concentrations. Incubation was terminated by the addition of SDS sample buffer lacking DTT, followed by heating at 100°C for 5 min, followed by SDS-PAGE. Shown is the proportion of ³²P radioactivity remaining bound to the protein relative to controls to which no sugar was added. A total of 70% or more of the radioactivity remained after incubation with the following compounds, each at a concentration of 0.1 mM: ribose-1-phosphate, ribose-5-phosphate, xylose-1-phosphate, glucose, glucose-1-phosphate, glucose-6-phosphate, fructose, fructose-1-phosphate, fructose-6-phosphate, mannose-1-phosphate, mannose-6-phosphate, ATP, or ADP. -, Not determined.