Notes: The authors describe the highly specific binding of a hexanucleotide Hex-S3 to the large subunit of HIV-1 reverse transcriptase. They expressed the RTs of various HIV strains and equine infectious anemia virus RT, as well as the p51 subunit of HIV-1 RT, in E. coli, then purified the enzyme. Enzyme concentrations were determined using an extinction coefficient at 280nm of 140000 M-1 cm-1. All RTs studied were determined to be free of nuclease contamination. The authors then studied the binding of a variety of hexanucleotides to these RTs. (3702)