Table 1.

Inhibition of homologous pairing by Rad51 in direct proportion to GC content of oligonucleotide substrates

% GC	Homologous pairing measured by FRET (relative signal, %)
16	100
29	72
40	41
71	04

The substrates were homologous single- and double-stranded 83-mer oligonucleotides with the GC base contents indicated. Secondary structure in the single-stranded oligonucleotides was minimized and reactions were constituted as described in Methods. The steady-state level of homologous pairing was assessed after incubation at 37°C for 30 min by measurement of fluorescence resonance energy transfer (FRET) as described previously (8, 21). The entries in italics were derived by interpolation from the other data.