Polynucleotides. 23. A synthesis of ribodinucleoside monophosphates using nucleoside 5'-phosphates

Efficient chemical synthesis of AppDNA by adenylation of immobilized DNA-5'-monophosphate

AppDNA is an intermediate in enzyme-catalyzed DNA ligation reactions, and its efficient enzymatic synthesis requires a donor-template duplex of at least 11 base pairs in length. An efficient chemical synthesis of AppDNA with the coupling of an adenosine 5'-phosphorimidazolidate to an immobilized DNA-5'-monophosphate as the key step is described. The adenylation efficiencies of DNA-5'-monophosphate were excellent for oligonucleotides containing less than 11 nucleotides and at least 50% for oligonucleotides containing 15-25 nucleotides.

Nucleotides. VI. Syntheses and spectral properties of some deazaadenylyl-deazaadenosines (dinucleoside monophosphates with unusual CD-spectrum) and closely related dinucleoside monophosphates

Nine dinucleoside phosphates containing 1-deaza-(1A) and 3-deazaadenosine (3A) were prepared. Hypochromicity and CD spectra of these dimers were determined. It was found that varying degrees of base-stacking are operative with these oligonucleotides and their CD spectra fall into three classes. The first class CD spectra which are more or less similar in profile to those of adenylyl-(3'-5')-adenosine includes the CD spectra of 1A2'p5'A, 1A3'p5A, 3A2'p5'A and 3A3'p5'A. The second class includes the CD spectra of A2'p5'1A and A3'p5'1A whose characteristic is that the positive Cotton band appears in the range of 280-310 nm. The third type CD spectra has the characteristics that the negative Cotton band appears in the longer wavelength region and th CD spectra are similar in profile to those of L-adenylyl-(3'-5')-L-adenosine which has the "left-handed helical" conformation. The CD spectra of A2'p5'3A, A3'p5'3A and 3A3'p5'A belong to this class. Another salient observation emerging from the CD-determination is that 3A3'p5'3A has the spectrum quite different from that of poly 3-deazaadenylic acid.

Studies on transfer ribonucleic acids and related compounds. IX. Ribooligonucleotide synthesis using a photosensitive o-nitrobenzyl protection at the 2'-hydroxyl group

o-Nitrobenzyl group was introduced to the 2'-hydroxyl function of uridine via 2',3'-O-(dibutylstannylene) uridine. The benzylated uridine was protected at the 5'-hydroxyl group with monomethoxytrityl chloride and condensed with 2',3'-O-dibenzoyluridine 5'-phosphate or N,N',2',3'-O-tetrabenzoyladenosine 5'-phosphate using dicyclohexylcarbodiimide (DCC). o-Nitrobenzyl ether linkage of the dinucleotides was removed by UV irradiation with wavelength longer than 320 nm. Deprotected UpU and UpA thus obtained were characterized by RNase A digestion.