. Author manuscript; available in PMC: 2012 Feb 8.

Published in final edited form as: Biochemistry. 2011 Jan 11;50(5):882–890. doi: 10.1021/bi101813h

Table 1.

Base pair opening rates of B-form GC-10 and GCX-10 duplexes at 10°C^a


Base	k_o (s⁻¹)^b		k_slope (s⁻¹ M⁻¹)^c
Base	GC-10	GCX-10	GC-10	GCX-10
T2	-^d	-^d	-^d	-^d
G4	1.7 ± 0.2	131 ± 11^e	44 ± 4	8400 ± 3200^e
G5	2.0 ± 0.2	204 ± 22^e	40 ± 4	-^d
T8	8.7 ± 0.5	219 ± 11^e	-^d	26400 ± 4000^e
G10	39 ± 4.1	-^d	-^d	-^d

The DNA sequence is indicated as well as the crosslinked bases in red. The guanine base G5 opposite to the crosslinked cytosine is indicated in bold.

The observed exchange rate at zero concentration ammonia catalyst (eq 2).

The initial slope of the hyperbolic curve of eq 2, corresponding to the apparent second-order rate constant for general base catalysis of exchange by ammonia, (k_op/k_cl) × k_b.

Exchange broadened beyond detectable limits.

Exchange rates from line width measurements and eq 3. A value for R₂^dip was taken from the narrowest imino linewidth of the GC-10 spectra minus its k_o as determined by imino exchange, 17.9 Hz.