Table 1.

Steady-State Kinetic Constants of Wild-Type and Mutant PMKs Determined for the Forward Reaction. ^a

Enzyme	Km(R-MVP),app (μM)	Vmax(R-MVP) (U/mg)	Km(ATP),app (μM)	Vmax(ATP) (U/mg)
WTb	34±3	46.4±1.0	107±14	52.0±1.1
K48M	131±7	0.036±0.001	236±16	0.035±0.001
K69M	110±8	0.11±0.01	268±22	0.09±0.01
R73M	100±8	0.018±0.001	94±16	0.015±0.001
R84M	1710±49	5.89±0.04	303±14	3.91±0.08
R93M	48±3	33.1±0.8	101±6	32.4±0.5
R110Mc	n.d	n.d	n.d	0.0026±0.0007
R111M	2040±225	0.95±0.04	792±102	0.69±0.03
R130M	102±9	14.8±0.4	229±16	13.2±0.3
R138M	47±7	17.4±0.6	518±61	19.9±0.8
R141Md	225±23	3.2±0.1	5200±474	3.6±0.1

^aSpectrophotometric assays were performed in 100 mM MOPS, 200 mM KCl, 1 mM DTT (pH 7.0) in the presence of 10 mM MgCl₂ at 30°C. Values were determined by fitting data to a Michaelis-Menten equation. Errors represent the standard error of the fit.

^bHerdendorf and Miziorko, Biochemistry 45 (2006)

^cSpecific activity determination under standard conditions using a fluorescent assay using the same buffer conditions. Error represents the standard deviation of 5 measurements.

^dAssay contained 20 mM MgCl₂. nd indicates not determined.