Anomalies in the sedimentation behavior of high molecular weight DNA isolated from Proteus mirabilis

✍ Scribed by Hans Triebel

• Publisher: Wiley (John Wiley & Sons)
• Year: 1968
• Tongue: English
• Weight: 610 KB
• Volume: 6
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1968.360060402

✦ Synopsis

The sedimentation properties of a P. mimbilis DNA sample have been investigated at different concentrations and rotor speeds. Pronounced speed effects occurred at high angular velocities. The s&w 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 a t 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 leading 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.