A Beckman Optima XL-I analytical ultracentrifuge is now available as part of a new UMMS core facility sponsored jointly by the Program in Molecular Medicine and the Department of Biochemistry and Molecular Pharmacology. This is a state-of-the-art instrument that facilitates rigorous characterization of the solution state behavior of macromolecules. The instrument is housed in Biotech II, suite 301 (Craig Peterson's Lab). The facility offers a part time technician who is dedicated to operation of the instrument. The XLA is available to all UMMS researchers, although preference will be given to the initial user group. If you wish to run samples, simply go to the web calendar link shown below and reserve a time slot. On the morning of your reserved time, bring your samples and reference buffers up to the facility. Make sure to download and fill out the sample form and bring that with you. The information contained in the sample form is important and should be filled out as completely as possible. The operator (Kim Crowley) will take your samples, assemble the cells, and start your run. When the run is finished you will need to come back with a CD-R(W) to obtain you data. We strongly urge you to access the recommended websites to investigate the available software packages suitable for data analysis.

Located in Suite 205a of Biotech II (Craig Peterson's Lab)

To sign up for time on the XLI go to the Analytical Centrifuge Sign-up Calendar

You may email Kim Crowleywith any additional questions.

  • Wavelength Range: 190-800 nm
  • Molecular Weight Range: 102-106 Da
  • Concentration Range (Absorbance): 5 µg/ml to about 1-2 mg/ml
  • Concentration Range (Interference): 25 µg/ml to about 4-5 mg/ml
  • Binding (Dissociation) Constant Range: Kd of 10-3-10-8 M

General considerations for setting up centrifugation experiments:

The sample must be as pure as possible and free from contaminating proteases. Prior to setting up each experiment samples should be dialyzed against buffer, and the dialysate used in the reference channel. If absorbance optics are to be used, buffer should be selected which does not absorb significantly in the chosen wavelength range. If there is concern for aggregation, you may want to spin your sample in a microfuge for a few minutes and check to make sure you are not seeing a decrease in absorbance.

Velocity runs are performed in 2-sector cells which each require 400 ul of sample, and 420 ul of buffer for the reference. Equilibrium runs are performed in the same 2-sector cells using 120 ul of sample and 140 ul of reference. We have two rotors with a capacity of 3 cells and 7 cells respectively. A slight excess of sample and a generous amount of buffer would be appreciated.

After your run is completed you should bring a blank CD to record your data.

Please download this sample information formthat needs to be filled out each time you bring in a sample. The information is ALL required. See the web site links below for more information.

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