H. L. Lewis, D. Muhleman, J. Ward
Aug 1, 1978
Citations
0
Influential Citations
34
Citations
Quality indicators
Journal
Radiation research
Abstract
We have developed a serologic assay for 5-hydroxymethyldeoxyuridine, (5-HMUdR) an ionizing radiation product of thymidine. Antibodies were prepared to a bovine serum albumin conjugate of 5-hydroxymethyluridine (5-HMUR). Using phage neutralization assay 0.1 nmole of 5-HMUR can be detected. The antiserum cross-reacted with thymidine but with no other naturally occurring DNA components. There was cross-reaction with uridine, 6-methyluracil, and the halogenated analogs of thymidine. Interference by cross-reaction with thymidine was eliminated by saturation of the assay with excess thymidine. Three micromolar (0.3 nmole/0.1 ml) 5-HMUR can be detected in the presence of 8 mM thymidine. The assay was applied to the estimation of 5-HMUdR produced by ..gamma.. irradiation of thymidine in O/sub 2/. The G value for product formation was 0.05. Irradiation at pH 14 greatly increased the yield. There was a threefold increase in G value when irradiated samples were heated at pH 9 or treated with 10/sup -3/ M ferrous ions, postirradiation procedures which convert thymidine methylperoxides to 5-HMUdR. This suggests that cross-reaction with the peroxide is not extensive. Estimation of 5-HMUdR in DNA irradiated in O/sub 2/ gave a G value roughly the same as that found in irradiation of thymidine. This yield is based on the assumptionmore » that antibody reacts equally with the 5-HMU moiety in DNA and as the mononucleoside. 5-HMUdR was detected as one nucleoside per 3 x 10/sup 6/ daltons of DNA.« less