Abstract: Oligonucleotides having tandem sequences of inverted polarity, i.e., oligonucleotides comprising regions of the formula: ##STR1## wherein --C-- symbolizes any method of coupling the nucleotide sequence of opposite polarity, are useful for forming an extended triple helix with a double-helical nucleotide duplex. The inverted polarity also stabilizes the single-strand oligonucleotides to exonuclease degradation.

Abstract: An improved method for the preparation of acyclic nucleotide analogues comprises first condensing a cyclic carbonate with a purine or pyrimidine base and then reacting the alkylated base with an activated phosphonate. Novel cyclic carbonates are employed to yield the desired phosphonylmethoxyalkyl nucleotide analogues.

Abstract: A composition comprising a compound of the formula: ##STR1## wherein: X is H or OH;Y is a group capable of hydrogen bonding to amino, guanidino, or imidazole function, or a group comprising an acidic hydrogen atom, a protected acidic group, or an anion;E is N or CR.sub.1, wherein R.sub.1 is H, OH, CN, F, Cl, Br, or I;A.sub.4, A.sub.5, and A.sub.6 are each independently N, CH, CR.sub.40 or CZ wherein R.sub.40 is R.sub.43, OR.sub.43, SR.sub.43, S(O)R.sub.43, S(O).sub.2 R.sub.43, or NR.sub.43 R.sub.44 wherein R.sub.43 comprises an alkyl of 1 to 3 carbon atoms, an acyl of 2 to 3 carbon atoms, or an alkyl of 1 to 3 carbon atoms substituted with an acyl of 2 to 3 carbon atoms, and R.sub.44 is H or an alkyl of 1 to 2 carbon atoms, and Z is a group capable of hydrogen bonding to carboxyl, or a group comprising a basic heteroatom, a protected basic heteroatom, or a cation.

Abstract: A compound having the structure: ##STR1## wherein R.sup.1 is an oligonucleotide;a is 1 and b is 0;A is C or CH;X is S, O, NH or NCH.sub.2 R.sup.6 ;Z is taken together with A to form an aryl ring structure comprising 6 ring atoms wherein the aryl ring carbon atoms are unsubstituted with other than H or at least 1 nonbridging ring carbon atom is substituted with R.sup.6 or .dbd.O;R.sup.6 is independently H, C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl, C.sub.2 -C.sub.6 alkynyl, NO.sub.2, N(R.sup.3).sub.2, C.tbd.N or halo, or an R.sup.6 is taken together with an adjacent Z group R.sup.6 to complete a phenyl ring; andR.sup.3 is a protecting group or H; and tautomers, solvates and salts thereof.

Abstract: Modified oligomers containing at least one internucleoside linkage of the formula Y.sup.1 CX.sub.2 y.sup.2 wherein at least one of Y.sup.1 and Y.sup.2 is sulfur and the other is oxygen and wherein each X is the same or different and is a stabilizing substituent are disclosed. These oligomers show superior binding properties and are thus useful for binding target substances in analytical uses. Also disclosed are improved methods for synthesis of oligomers containing linkages of the general formula --YCX.sub.2 Y-- wherein each Y may be independently oxygen or sulfur.

Abstract: The present invention relates to an oligonucleotide or analog thereof conjugated to a molecule comprising a structure, which structure (a) is of substantially fixed conformation; (b) contains, is directly attached to, or is attached to a carbon atom that is directly attached to, an first amine; and (c) contains, is directly attached to, or is attached to an atom that is directly attached to a phosphate, a second amine, or a cationic sulfur. In a preferred embodiment, the structure consists of at least a nonaromatic cyclic portion or substituted derivative thereof. In a specific embodiment, the structure is a nonaromatic cyclic compound. In another embodiment, the molecule is a steroid. In yet another particular aspect, the structure is an aromatic compound. In another embodiment, the structure can bind to a nucleic acid sequence in a nonintercalative manner.

Abstract: Oligonucleotides with enhanced hybridization binding possessing 5-propynyluracil and/or 5-propynylcytosine in place of uracil and cytosine, respectively. These oligonucleotides are useful in traditional hybridization assays for detection of a specific DNA sequence.

Abstract: Oligonucleotide analogs having one or more substitute linkages of the formula 2'/3'--S--CH.sub.2 --CH.dbd.5' or 2'/3'--O--CH.sub.2 --CH.dbd.5' between adjacent nucleomonomers are disclosed. The substitute linkage replace the usual phosphodiester linkage found in unmodified nucleic acids. The oligonucleotide analogs are easy to synthesize, stable in vivo, resistant to endogenous nucleases and are able to hybridize to target nucleic acid sequences in a sequence specific manner.

Abstract: Oligonucleotide analogs wherein one or more phosphodiester linkages between adjacent nucleotides are replaced by an formacetal/ketal type linkage are resistant to nucleases and do not need to exhibit the diastereomerism characteristic of many other oligonucleotide analogs, and thus are capable of strong hybridization to target RNA or DNA. These oligonucleotide analogs are useful in therapies which modulate gene expression using "antisense" or other specifically binding oligomers.

Abstract: A method is provided for making 3' and/or 5' end-capped oligonucleotides so as to render the oligonucleotide resistant to degradation by exonucleases. The exonuclease degradation resistance is provided by incorporating two or more phosphoramidate and phosphorocmonothioate and/or phosphorodithioate linkages at the 5' and/or 3' ends of the oligonucleotide, wherein the number of phosphoramidate linkages is less than a number which would interfere with hybridization to a complementary oligonucleotide strand and/or which would interfere with RNAseH activity when the oligonucleotide is hybridized to RNA.

Abstract: Oligonucleotide sequences modified by conjugation to at least one unsubstituted or substituted anthraquinone at other than the 5' terminus have favorable properties in enhancing hybridization to target DNA or RNA without loss of specificity and show enhanced stability to nucleases.

Abstract: Novel hydrogen-phosphonodithioate compositions are provided which are particularly useful for forming internucleotide and internucleoside linkages in oligonucleosides or oligonucleotides. The oligonucleotides and analogs thereof made by using the hydrogen-phosphonodithioate compositions may be therapeutically useful as antiviral and anticancer agents and may have other therapeutic or diagnostic uses. A method for making the hydrogen-phosphonodithioates is provided as well as a method for converting same to an activated intermediate for substitution on the phosphorus atom.