TABLE 3.

Kinetic constants for inhibition of nucleotide incorporation by PFA

Enzyme	IC50a	Foldb change	Kic	Fold change
	μm		μm
UL54d	0.87e	Referencef	0.076	Reference
RT	0.60	1.4Sg	1.1	14
gp43	333	380R	NAh	NA
gp43	333	Reference	NA	NA
A	7.5	44S	NA	NA
ABC	3.3	100S	NA	NA
A	7.5	Reference	0.99	Reference
A/V781I	19.7	2.6R	1.8	1.8R
ABC	3.3	Reference	0.55	Reference
ABC/R784A	37	11R	5.9	11R
ABC/Q807A	27	8.2R	6.1	11R

^a IC₅₀ is the inhibitory concentration of PFA that reduced the nucleotide incorporation activity of enzyme by 50%. Values were calculated by fitting at least 10 data points to a sigmoidal dose-response (variable slope) equation using GraphPad Prism (version 5.0).

^b Fold change is calculated as the ratio of the IC₅₀ or K_i values of the reference and the query enzyme in the subgroup such that the ratio is more than 1.

^c K_i is the inhibitor dissociation constant. Values were calculated by globally fitting the 42-data point K_i experiment to the general mixed model of inhibition using GraphPad Prism (version 5.0).

^d The HCMV polymerase UL54 was expressed in the in vitro transcription/translation system.

^e Standard deviations were determined on the basis of at least three independent experiments and represent a maximum of 25% of the reported value.

^f Reference defines the enzyme whose inhibitory constants were used as a reference value in the subgroup. Subgroups of enzymes are separated by an extra row.

^g Superscript R and S indicate resistance and sensitivity, respectively, and illustrate fold changes in resistance or sensitivity to PFA with respect to the reference enzyme in the subgroup.

^h NA means not available.