Synthesis of an Oligonucleotide Probe Containing Trityl-protected Sulphydryl Group and Tagging with a Fluorescent Dye

The sulphydryl group of mercaptoethanol is protected by a trityl group and then reacted with methoxymorpholinochlorophosphite to give the corresponding phosphoramidite (III). The phosphoramidite has been used to introduce tritylmercapto ethyl group to the 5′ terminus of an oligonucleotide by using a solid phase method in a DNA synthysizer. After deprotection by Ag +, the mercaptoethyl group carried by the oligonucleotide is tagged with a fluorescent dye. Designed probe for screening lmb H gene hybrids with plasmids, the useful method is proved by the results. It could be detected at a limit of lpmol.