Low-angle light scattering of deoxyribonucleic acid.

An instrument of new design has been built in order to perform lowangle light-scattering measurements to angles as low as 16 degrees . Native deoxyribonucleic acid preparations of different molecular weights have been studied using this apparatus with a new clarification technique. The molecular weights obtained from the low-angle data have been compared with those calculated for the same samples when using the results in the 30-150 degrees range. The two sets of data yield the same molecular weights up to values of about 6 x 10(6). Higher molecular weights are underestimated to a variable extent when measurements in the usual angular region (30-150 degrees ) are used.