title: Synthesis and properties of oligodeoxyribonucleotide-polyethylene glycol conjugates.
abstract: Pools of oligonucleotide conjugates consisting of 10-400 different molecular species were synthesized. The conjugates contained a varying number of ethylene glycol units attached to 3'-terminal, 5'-terminal and internal positions of the oligonucleotides. Conjugate synthesis was performed by phosphoramidite solid phase chemistry using suitably protected polyethylene glycol phosphoramidites and PEG-derivatized solid supports containing polydisperse PEGs of various molecular weight ranges. The pools were analyzed and fractionated by chromatographic and electrophoretic techniques, and the composition of isolated conjugates was revealed by matrix-assisted laser desorption/ionization mass spectrometry. The number and attachment sites of coupled ethylene glycol units greatly influence the hydrophobicity of the conjugates, as well as their electrophoretic mobilities. Conjugation had little effect on the hybridization behavior of oligonucleotide conjugates with unmodified complementary oligonucleotide strands. Melting temperatures were between 67 and 73 degrees C, depending on the size and number of coupled PEG chains, compared to 68 degrees C for the unmodified duplex. Conjugates with PEG coupled to both 3'- and 5'-terminal positions showed a more than 10-fold increase in exonuclease stability.
authors.affiliation: Institut für Organische und Bioorganische Chemie, Humboldt-Universität zu Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Jäschke
authors.forename: J P
authors.initials: JP
authors.lastname: Fürste
authors.forename: E
authors.initials: E
authors.lastname: Nordhoff
authors.forename: F
authors.initials: F
authors.lastname: Hillenkamp
authors.forename: D
authors.initials: D
authors.lastname: Cech
authors.forename: V A
authors.initials: VA
authors.lastname: Erdmann
mesh_terms: D001483:Base Sequence; D005092:Exonucleases; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009691:Nucleic Acid Denaturation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis* / Q000302:isolation & purification; D009943:Organophosphorus Compounds / Q000737:chemistry; D043264:Phosphodiesterase I; D010727:Phosphoric Diester Hydrolases; D011089:Polydeoxyribonucleotides / Q000138:chemical synthesis* / Q000302:isolation & purification; D011092:Polyethylene Glycols / Q000737:chemistry*; D013388:Succinimides / Q000737:chemistry; D013696:Temperature; D014320:Triphenylmethyl Compounds / Q000737:chemistry
chemical_list: D009838:Oligodeoxyribonucleotides; D009943:Organophosphorus Compounds; D011089:Polydeoxyribonucleotides; D013388:Succinimides; D014320:Triphenylmethyl Compounds; D011092:Polyethylene Glycols; D005092:Exonucleases; C022650:spleen exonuclease; D010727:Phosphoric Diester Hydrolases; D043264:Phosphodiesterase I