Table 2.

Biochemical properties of TKT ^P and TKT ^C

Parameter		TKT C	TKT P
Molecular weight		73 kDa	73 kDa
		280 kDa (tetramer)	280 kDa (tetramer)
Optimal activity conditions:		50 mM Tris–HCl, pH 7.5, 2 mM Mn2+, 2 μM THDP, 55°C	50 mM Tris–HCl, pH7.7, 5 mM Mn2+, 1 μM THDP, 55°C
Optimal pH		7.2-7.4	7.2-7.4
Optimal temperature		62°C	62°C
Temperature stability		< 60°C	< 60°C
Kinetics
X5P	KM	0.15 ± 0.01 mM	0.23 ± 0.01 mM
	Vmax	34 ± 1 U/mg	45 ± 28 U/mg
	kcat	40 s-1	54 s-1
	kcat/KM	264 s–1 mM–1	231 s–1 mM–1
R5P	KM	0.12 ± 0.01 mM	0.25 ± 0.01 mM
	Vmax	11 ± 1 U/mg	18 ± 1 U/mg
	kcat	13 s-1	21 s-1
	kcat/KM	109 s–1 mM–1	84 s–1 mM–1
GAP	KM	0.92 ± 0.03 mM	0.67 ± 0.01 mM
	Vmax	85 ± 3 U/mg	42 ± 1 U/mg
	kcat	99 s-1	48 s-1
	kcat/KM	108 s–1 mM–1	71 s–1 mM–1
F6P	KM	0.72 ± 0.11 mM	0.25 ± 0.01 mM
	Vmax	71 ± 11 U/mg	96 ± 5 U/mg
	kcat	82 s-1	112 s-1
	kcat/KM	115 s–1 mM–1	448 s–1 mM–1

Values for K_M (mM), V_max (U/mg), and catalytic efficiency (k_cat/K_M = s^-1 mM^-1) were determined for two independent protein purifications and mean values and arithmetric deviations from the mean are given.