Glycerate kinase of the hyperthermophilic archaeon Thermoproteus tenax: new insights into the phylogenetic distribution and physiological role of members of the three different glycerate kinase classes

Table 1 Comparison of kinetic and biochemical properties from characterized class II glycerate kinases (MOFRL family)

		Archaea			Bacteria
		Crenarchaea	Euryarchaea
		T. tenax ¹	P. torridus ²	T. acidophilum ³	H. methylovorum ⁴
Growth optimum (°C)		90	60	59	28
Molecular mass
Subunit (kDa)		44	50	45	52
Native (kDa)		48,3	95	49,3	41
Calculated (kDa)		42,4	46,6	45,8	(46.5)⁵
Oligomeric structure		Monomer	Dimer	Monomer	Monomer
Kinetic Parameters
D-Glycerate	K_m (mM)	(0.02)⁶	0,34	(0.56)⁷	0,13
	V_max (U mg^-1)	(5.05)⁶	435	(118)⁷	181
	k_cat (min^-1)	214	20271	5404	8417
	k_cat/K_m (min^-1mM^-1)	8913	59621	9651	64742
ATP	K_m (mM)	(0.03)⁶	0,51	(0.23)⁷	0,13
	V_max (U mg^-1)	(4.41)⁶	432	(118)⁷	181
	k_cat (min^-1)	187	20131	5404	8417
	k_cat/K_m (min^-1mM^-1)	7187	39473	16889	64742
Reaction product		2-PG	2-PG	2-PG	2-PG
Temperature optimum (°C)		90	60	70	50
Substrate specificity (%)
L-Glycerate		30	34	nd	13
Phosphate donor specificity (%)
ATP		100	100	100	100
GTP		20	37	0–4	59
CTP		16	24	0–4	59
UTP		10	39	0–4	64
TTP		16	nd	nd	nd
Metal ion specificity (%)
Mg²⁺		100	100	100	100
Co²⁺		56	11	8	75
Mn²⁺		59	11	10	72
Ni²⁺		30	25	0	29
Ca²⁺		15	nd	0	0
Inhibition by ADP		+	nd	nd	+

¹this study; ² [32]; ³ [30] ⁴ [33]; ⁵since no information of the encoding gene is available, the mean value of subunit and native molecular mass was formed and used for the calculation of the k_cat/K_m value; ⁶since glycerate inhibition is observed for the T. tenax enzyme the estimated values for glycerate concentration up to 0.3 mM are given; ⁷determined for DL-Glycerate; nd, not determined; +, detected.

ISSN: 1471-2164