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I'm attempting to replicate a cell biology method from a 1958 Laboratory Investigation paper. The protocol is for the isolation of an extracellular matrix protein, and a key step is a centrifugation carried out for 2 hours at 2300 rpm. Apparently it was not common practice to list make, model, and rotor size of centrifuges, so I am a little lost as to what settings to use on my own centrifuge to get the same rcf.

Are there any good starting points for estimating the proper settings? e.g. who the major centrifuge suppliers were at the time or what models would be seen as 'standard' for a cell biology lab?

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  • $\begingroup$ Do they at least list what kind of tubes the samples were in while spun? Knowing the size of the tube would help narrow down possible rotor sizes. $\endgroup$ – user137 Dec 14 '14 at 5:12
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    $\begingroup$ CAn you provide a link to that article. $\endgroup$ – WYSIWYG Dec 14 '14 at 6:47
  • $\begingroup$ @user137 Good point! They use "250 mL centrifuge bottles" $\endgroup$ – Chastain Dec 14 '14 at 15:39
  • $\begingroup$ @WYSIWYG here is the pubmed link, but I don't know where to find the article online. ncbi.nlm.nih.gov/m/pubmed/13540204 $\endgroup$ – Chastain Dec 14 '14 at 15:39
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I am not sure about what they used in 1958 (perhaps Sorvall). However you may look at recent papers for ECM protein isolation (if that was your objective).

Have a look at this article.

From materials and methods:

ECM protein isolation.

Fibroblasts or A431 cells were removed from the surface of the culture plate with 2 mM EDTA in PBS for 3–5 min at 37⁰C. Detached cells were discarded, and remaining ECM proteins attached to the surface of culture plates were washed with the same solution. Cell removal was controlled under the microscope. After cells were completely removed, matrix proteins were covered with 5% acetic acid and incubated at 4⁰C overnight. Then, acetic acid was removed and exchanged with a buffer containing 125 mM Tris-HCl, pH 6.8, 0.1% SDS, 10% glycerol, 1% DDT, 0.05 mM PMSF, protease inhibitor cocktail (Roche, Germany), and incubated at 37⁰C for 1 h. Proteins were removed with a scraper. The procedure was repeated three times. All protein extracts, including acetic acid, were combined and ECM proteins were precipitated by five volumes of acetone. After incubation at –20⁰C overnight and centrifugation at 7000 g for 15 min, the protein pellets were dissolved in an appropriate buffer for further analysis by one- or two-dimensional gel electrophoresis.

In addition, we obtained a Triton X-100-soluble fraction of ECM proteins. Cells were removed as described above; dishes were filled with 1% Triton X-100 and incubated at 37⁰C for 30 min. The extraction was repeated three times. The following procedure of ECM extraction was the same as described above. Samples obtained from both fractions were dissolved in a buffer for one-dimensional (Laemmli) or two-dimensional (rehydration buffer containing 8 M urea, 2% CHAPS, 20 mM DDT, 0.1% Triton X-100) electrophoresis. Proteins that remained after Triton X-100 extraction were dissolved in Laemmli sample buffer.

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  • $\begingroup$ Thanks! That seems like a really good way to get the ECM into a pellet, but the purpose of the centrifugation in the article is actually to keep the ECM protein in the supernatant while letting the tissue it is digested from pellet. $\endgroup$ – Chastain Dec 15 '14 at 20:12
  • $\begingroup$ @Chastain The tissue is removed prior to protein precipitation. $\endgroup$ – WYSIWYG Jan 13 '15 at 7:46

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