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Anomalies in the sedimentation behavior of high molecular weight DNA isolated from Proteus mirabilis
Author(s) -
Triebel Hans
Publication year - 1968
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1968.360060402
Subject(s) - sedimentation , sedimentation coefficient , chemistry , proteus mirabilis , convection , terminal velocity , plateau (mathematics) , concentration gradient , ultracentrifuge , analytical chemistry (journal) , chromatography , mechanics , geology , geomorphology , physics , sediment , mathematical analysis , biochemistry , mathematics , escherichia coli , gene , enzyme
Abstract The sedimentation properties of a P. mirabilis DNA sample have been investigated at different concentrations and rotor speeds. Pronounced speed effects occurred at high angular velocities. The s 20, w 0 value evaluated from low‐speed experiments amounts to 61 S., indicating a mean molecular weight of 105 million. Anomalous concentration distributions in the ultracentrifuge cell have been observed at low speeds. At the boundary, a pile‐up of concentration occurs which exceeds the total plateau concentration. The concentration elevation decreases with increasing time due to convection which is caused by the existence of a negative density gradient. Despite this convection, accurate mean sedimentation coefficients could be obtained even at extremely low concentrations. A careful analysis of sedimentation coefficient distributions shows, however, that the lending and trailing tails of the boundaries are disturbed by convection. Thus it may be expected that the effect produces difficulties in determining true sedimentation coefficient distributions of polydisperse DNA samples of very high molecular weight.