TABLE 2.

Effect of H932Y/A mutations on kinetic parameters governing discrimination

Kinetic parameters governing misincorporation opposite a template T catalyzed by H932Y and H932A are summarized as derived from the data shown in Figs. 3 and 5. The S.E. estimates (±) were derived from the covariance matrix obtained by nonlinear regression. The upper and lower limits shown in parentheses were derived by confidence contour analysis (21).

Enzyme/nucleotide	1/K1	k2	k−2	k3
	μm	s−1	s−1	s−1
WT
TTP	81.8 ± 10.9	0.01 ± 0.004	(0)	Fast
	(40–90)	(0.006–0.01)
dCTP	1,030 ± 193	0.06 ± 0.018	(0)	Fast
	(810–1,300)	(0.05–0.08)
dGTP	1,300 ± 1,600	6.6 ± 7.4	(0)	Fast
	(836–4,100)	(4.5–20)
H932Y
TTP	1,630 ± 310	0.1 ± 0.02	0.01 ± 0.003	0.0004 ± 0.0005
	(1,300–1,920)	(0.08–0.1)	(0.01–0.014)	( 0.0003–0.0006)
dCTP	22,200 ± 3,420	0.02 ± 0.005	0.0004 ± 0.003	0.0003 ± 0.002
	(17,800–6.7 × 1011)	(0.015–8.3 × 105)	(0.0002–0.002)	(2.8 × 10−8-0.001)
dGTP	24,000 ± 9,600	1.2 ± 0.4	(0)	Fast
	(18,300–1.5 × 105)	(1–7)
H932A
TTP	9,400 ± 2,700	0.47 ± 0.15	0.013 ± 0.0056	0.0003 ± 0.0004
	(6,600–26,500)	(0.39–1.86)	(0.01–0.02)	(2 × 10−5-0.0007)
dCTP	40,900 ± 9,470	0.038 ± 0.012	0.0009 ± 0.0006	0.0005 ± 0.001
	(26,000–1.9 × 105)a	(0.02–0.18)	(0.0005–0.0017)	(0.0002–0.0008)
dGTP	5,150 ± 1,500	0.27 ± 0.06	(0)	Fast
	(4,100–10,000)	(0.23–0.45)

^a No upper limit was found up to the value reported.