Assembled GFPuv was diluted to 250 ng/ml in 10 mM Tris-HCl, pH 7.8, 50 mM NaCl and heated to 95 C for 5 min followed by cooling 0.1 C/s to 25 C. Heteroduplex for consensus filtering was split into three pools and digested to completion with NlaIII (NEB), TaqI (NEB) or NcoI plus XhoI (Promega) for 2 h following the manufacturer's protocols. Digests were purified using the Qiagen QIAquick PCR purification kit with elution in dH 2 O. Samples were pooled and the concentration was determined by measuring A 260 .