1.Intramolecular cyclization in irradiated nucleic acids: correlation between high-performance liquid chromatography and an immunochemical assay for 8,5'-cycloadenosine in irradiated poly(A).
Fuciarelli AF, Shum FY, Raleigh JA. Radiat Res. 1987 Apr;110(1):35-44.
A correlation between high-performance liquid chromatography (HPLC) analysis and an in situ enzyme-linked immunosorbent assay (ELISA) for 8,5'-cycloadenosine formation in irradiated poly(A) has been established. The correlation shows that the ELISA precisely reflects changes in the combined yield of R- and S-8,5'-cycloadenosine but that a correction factor must be applied to the ELISA values for accuracy. The HPLC analysis reveals that the intramolecular cyclization proceeds stereoselectively in irradiated poly(A) to preferentially produce the R isomer at pH 7.0 which is similar to the result for irradiated adenosine but in contrast to the result for 5'-AMP where the S isomer predominates at neutral pH. The HPLC analysis shows that two events originating in hydroxyl radical attack at the sugar phosphate backbone in poly(A); that is, adenine release and 8,5'-cycloadenosine formation have somewhat different dose-yield responses. The formation of 8-hydroxyadenosine was detected in the HPLC chromatograms of poly(A) irradiated under N2O at neutral pH, and the yield of this compound was similar to the yield observed in 5'-AMP or adenosine irradiated under similar conditions.
2.Stereoselective intramolecular cyclization in irradiated nucleic acids: R- and S-8,5'-cycloadenosine in polyadenylic acid.
Fuciarelli AF, Shum FY, Raleigh JA. Biochem Biophys Res Commun. 1986 Jan 29;134(2):883-7.
The yields of R- and S-8,5'-cycloadenosines have been measured in poly A irradiated with gamma rays in the absence of oxygen. High performance liquid chromatographic analysis of the nucleoside analogues obtained by hydrolysis of the irradiated poly A shows that the R isomer predominates to the extent of 2.5-fold at doses of ionizing radiation in the range of 0-400 Gy.
3.Comparison of solid state and solution conformations of R and S epimers of 8,5'-cycloadenosine and their relevance to some enzymatic reactions.
Birnbaum GI, Cygler M, Dudycz L, Stolarski R, Shugar D. Biochemistry. 1981 May 26;20(11):3294-301.
The C(5')-R epimer of 8,5'-cycloadenosine crystallizes in the monoclonic space group P2(1) (Z = 2) with unit cell dimensions a = 5.755 (1), b = 16.895 (1), and c = 5.511 (1) A and beta = 104.16 (1) degree. X-ray intensity data were measured on a diffractometer, and the crystal structure was determined by direct methods. Least-squares refinement converged at R = 0.037 for 1008 reflections. The conformation about the glycosyl bond is anti, as imposed by the 8,5' cyclization, with XCN = 29.8 degrees. The ribose ring adopts the unusual C(1')endo-O(4')exp (o1T) conformation with pseudo-rotation parameters P = 289.0 degrees and tau m = 490 degrees. The six-membered ring formed by the 8,5' linkage is approximately a half-chair with C(4') and O(4'), respectively, above and below a plane defined by the other four atoms. These results are compared with those previously reported for the corresponding S epimer [Haromy, T. P., Raleigh, J., & Sundaralingam, M.
4.An immunochemical probe for 8,5'-cycloadenosine-5'-monophosphate and its deoxy analog in irradiated nucleic acids.
Fuciarelli AF, Miller GG, Raleigh JA. Radiat Res. 1985 Dec;104(3):272-83.
Polyclonal antisera specific for 8,5'-cycloadenosine-5'-monophosphate (8,5'-cyclo-AMP) or its deoxy analog (8,5'-cyclo-dAMP) were elicited by immunizing rabbits with a conjugate prepared by the method of Johnston et al. [Biochemistry 22, 3453-3460 (1983)]. A competitive enzyme-linked immunosorbent assay (ELISA) was developed and used to detect the formation of these products in irradiated solutions of polyadenylic acid [poly(A)] or DNA which were saturated with nitrous oxide, nitrogen, or oxygen. The 8,5'-cyclo-AMP or 8,5'-cyclo-dAMP moieties could be detected in poly(A) at 1.0 krad and in native DNA at 10 krad, respectively. The yield of 8,5'-cyclo-dAMP was found to be two to three times higher in irradiated double-stranded DNA than in single-stranded DNA. The hydroxyl radical appears to initiate 8,5'-cyclonucleotide formation in irradiated nucleic acids, as demonstrated by the inhibition of 8,5'-cyclo-AMP formation in irradiated poly(A) by dimethyl sulfoxide.