The number-average molecular weight, M_{n}, of a random distribution of single-stranded DNA molecules can be calculated directly from the profile obtained after alkaline sucrose gradient sedimentation. For such a distribution M_{n} can also be obtained from the weight-average molecular weight, <tex-math>$M_{w}$</tex-math>, and the median molecular weight, <tex-math>$M_{{\textstyle\frac{1}{2}}}$</tex-math>. When the size distributions are not random the latter procedures are erroneous. Nonrandom distributions of the type to be expected after X-irradiation of cellular DNA and its repair were generated by computer using Monte Carlo procedures. These distributions were then utilized as examples to illustrate the types of error which can be encountered when <tex-math>$M_{w}$</tex-math> and <tex-math>$M_{{\textstyle\frac{1}{2}}}$</tex-math> are used to calculate M_{n} from nonrandom distributions.

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1 April 1973

Research Article|
April 01 1973

# Review and Evaluation of Molecular Weight Calculations from the Sedimentation Profiles of Irradiated DNA

*Radiat Res*(1973) 54 (1): 152–162.

Citation

U. K. Ehmann, J. T. Lett; Review and Evaluation of Molecular Weight Calculations from the Sedimentation Profiles of Irradiated DNA. * Radiat Res* 1 April 1973; 54 (1): 152–162. doi: https://doi.org/10.2307/3573873

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