title: Boron-containing oligodeoxyribonucleotide 14mer duplexes: enzymatic synthesis and melting studies.
abstract: A set of three 14mer oligodeoxyribonucleotides of sequence d(5'-CTATGGCCTCAG*CT-3'/3'-GATACCGGAGTCGA-5') containing G* variants either as 2'-deoxyguanosine phosphate (unmodified), N7-cyanoborane 2'-deoxyguanosine phosphate (base-modified) or 2'-deoxyguanosine boranophosphate (backbone-modified) were synthesized by template-directed primer extension. Both the N7-cyanoborane 2'-deoxyguanosine triphosphate and 2'-deoxyguanosine alpha-boranotriphosphate nucleotides are good substrates for Sequenase. We infer that a single Sp boranophosphate linkage (which has a stereochemistry equivalent to the corresponding Rp thiophosphate analog) is formed in the backbone-modified 14mer. Thermally induced helix-coil transitions were monitored for the hybridized duplexes using UV and circular dichroism (CD) spectroscopy. The CD spectra of the two types of boron-modified hybrids closely resemble the unmodified parent duplex, forming B-type helices in 150 mM NaCl, 1 mM EDTA, 10 mM phosphate, pH 7.4, buffer. UV melting results indicate that both hybrids have stabilities comparable with the parent duplex as measured by Tm or delta G degree 25. These studies indicate that singly modified base- or backbone-boronated DNA are good analogs of normal DNA.
authors.affiliation: Department of Chemistry, Duke University, Durham, NC 27708-0346, USA.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: K
authors.initials: K
authors.lastname: Porter
authors.forename: F
authors.initials: F
authors.lastname: Huang
authors.forename: B R
authors.initials: BR
authors.lastname: Shaw
mesh_terms: D001483:Base Sequence; D001880:Boranes / Q000737:chemistry*; D002942:Circular Dichroism; D003849:Deoxyguanosine / Q000031:analogs & derivatives*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D001880:Boranes; D009838:Oligodeoxyribonucleotides; D003849:Deoxyguanosine