Water → 2-(6-Hydroxy-3-oxo-3H-xanthen-9-yl)benzoic acid

Participants

Reaction Steps

A solution of fluorescein isothiocyanate (Aldrich) 10 μl of 10% solution in DMF) was added to the aminooligonucleotide (0.25 A260 units) in 0.2 M borate buffer, pH 8.6, 100 μl). The mixture was shaken in the dark overnight; then water (400 μl) was added and the mixture was desalted by gel filtration on a NAP-5 column (Pharmacia). The filtrate (1 ml) was collected, concentrated, and repurified by gel filtration. Reversed phase HPLC showed that the oligomers were converted essentially completely to the fluorescein conjugated derivatives: for the derivative of 3'-amino-oligomer 18, elution time 21.5 min (compared to 19.0 min for the starting amino-oligomer); for the derivative of 5'3'-diamino-oligomer 19, elution time 23.6 min (compared to 18.5 min for the starting diaminooligomer). The UV spectra show the presence of both the thymidine and fluorescein moieties: for derivative of 18, λmax 266, 456, 480 nm, λmin 240, 332, 468 nm; for derivative of 19, λmax 266, 460, 482, μmin 250, 332, 470 nm.

Provenance & Evidence