. Author manuscript; available in PMC: 2013 Sep 16.

Published in final edited form as: Biochemistry. 2010 Jan 12;49(1):195–206. doi: 10.1021/bi901614m

Table 5.

Dissociation rate constants for ligands from wild type S. pneumoniae DHFR and Sp9 mutant at 25 °C in MTEN Buffer at pH 7.0.

Enzyme	Ligand	Enzyme species	Trapping ligand	k_off (s⁻¹) pH 7.0
S. pneumoniae (wt)	H₄F	E.H₄F.NH	MTX	ND^*
		E.H₄F.N⁺	MTX	5.7 ± 0.4
		E.H₄F	MTX	3.8 ± 0.1

	NADP⁺	E.H₄F.N⁺	NADPH	> 250 ^†

	NADPH	E.H₄F.NH	NADP⁺	ND^*

Sp9	H₄F	E.H₄F.NH	MTX	ND^*
		E.H₄F.N⁺	MTX	12.0 ± 1.6
		E.H₄F	MTX	6.7 ± 0.2

Not determined due to the weaker signal.

^†

The value is close to the experimental detection limit and estimated to be 400 s⁻¹ from the simulation.