Chemically induced dynamic nuclear polarization studies of guanosine in nucleotides, dinucleotides, and oligonucleotides

Journal Article · Mon Apr 23 23:00:00 EST 1984 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00304a006· OSTI ID:5864097

McCord, E F; Morden, K M; Pardi, A; Tinoco, I Jr; Boxer, S G

The nuclear magnetic resonance (NMR) technique of chemically induced dynamic nuclear polarization (CIDNP) has been used to study the reactions between photoexcited flavins and a wide variety of nucleotides, dinucleotides, and oligonucleotides. The greatest emphasis is placed on the purine nucleosides adenosine (A), inosine (I), and guanosine (G), particularly guanosine. The presence of G suppresses the CIDNP effect for A, although A by itself shows very strong CIDNP. Very intense CIDNP signals are observed for the H8 proton in G-containing mononucleotides, but no nuclear polarization is detected for the sugar H1' proton. In contrast, both H8 and H1' protons exhibit CIDNP for G in a wide range of dinucleotides and higher oligonucleotides. Several possible mechanisms are analyzed to explain the H1' polarization, and it is concluded that the sugar H1' proton probably obtains spin density through interaction with guanine nitrogen 3. The proximity of the H1' proton to N3 depends explicity on the glycosidic torsion angle, chi. CIDNP studies of several model compounds in which chi is fixed are consistent with this suggestion. CIDNP for the self-complementary tetramer ApGpCpU was studied as a function of temperature. Strong CIDNP from G is only observed at temperatures above the double-strand melting temperature, suggesting that CIDNP is only detected in single-stranded regions, where the base is accessible to solvent. The use of brominated riboflavin as the photoreagent in place of riboflavin is shown to selectively invert the sign of A, I, and 1-methylguanosine polarization, providing a convenient method for distinguishing the NMR spectra of these residues in complex oligonucleotides.

• Research Organization: Stanford Univ., CA
• DOE Contract Number: AT03-82ER60090
• OSTI ID: 5864097
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 23:9; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AROMATICS
AZAARENES
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
GUANOSINE
HETEROCYCLIC COMPOUNDS
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
POLARIZATION
PURINES
RESONANCE
RIBOFLAVIN
RIBOSIDES
SPECTRA
TEMPERATURE DEPENDENCE
VITAMIN B GROUP
VITAMINS