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. Author manuscript; available in PMC: 2008 Aug 15.
Published in final edited form as: J Med Chem. 2006 Jul 13;49(14):4344–4355. doi: 10.1021/jm060016l

Table 2.

Calculated parameter values (± 95% confidence limits) for the rate constants and equilibrium constants depicted in Scheme 2 for the reactions of 1, 2, I′-1 and I′-2 at pH 3.0 or 7.4 and 37 °C

Parameter value pH
(h−1) 3.0 7.4
1(I′-1) 2(I′-2) 1(I′-1) 2(I′-2)
k1 0a 0a 61.2 ± 60.2 14.5± 4.9
k−1 0.2 ± 0.03 0.004 ± 0.0003 48a 0.3a
Keq 0 0 1.3 ± 0.2 60.7 ± 16.7
k3 0.5 ± 0.07 0.05 ± 0.002 0.8 ± 0.1 0.4 ± 0.05
k4 0b 0b 0b 0b
k5 0.5 ± 0.08 0.2 ± 0.03 0.2 ± 0.03 0.02 ± 0.004
k6c ∼0c ∼0c 1.39 1.39
k−6c NDc NDc 0.138 0.138
k7 0.01 ± 0.002 0.01 ± 0.0005 0.3 ± 0.06 0.4 ± 0.1
R2 0.97 0.99 0.98 0.96
a

Values were obtained from Keq = k1/k−1

b

k4 was initially included as a fitted parameter but the best fit value was always negligible and not significantly different from zero

c

k6 and k−6 were determined separately by monitoring the conversion of the lactone and carboxylate (at pH 3 reaction of the carboxylate was too rapid to measure and no conversion of the lactone to carboxylate could be detected)