General Information
Medco Labs uses a P.E.Biosystems Precise automated sequencer. This instrument is able to perform four sequences in a series, which allows for the laboratory to be as efficient as possible for our customer's time constraints. The sequencer uses traditional Edman chemistry with detection to upper femtomole to low picomole level.
Sample Guidelines
There is no minimum amount of sample, which will be accepted for sequencing. The decision to sequence is the user's alone. However, consultation with Medco Laboratories personnel is recommended and only those samples, which have a high degree of probability for yielding useful information, will be submitted for analysis. Suitable solvents include: water, 0.1% acetic acid, 0.1% trifluoroacetic acid, ammonium bicarbonate, ammonium acetate, and sodium docecyl sulfate (up to 0.1% highest purity).
Any or all of the following information should be supplied if available:
Proteins:
Assessment of purity. Useful information can be obtained on unblocked proteins of 80 percent or higher purity. The number of N-termini, which comprise the impurity, influences the quality of the sequencing results. Approximate molecular weight. N-terminal amino acid identity, if known. Presence of carbohydrate, lipid, or other amino acid modifications, if known. Cysteine residues must be derivatized before sequencing!
Peptides:
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Origin and oxidation state.
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Amino acid composition analysis (this is highly recommended because confirmation of sequence by sequence is easily performed).
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N-terminus, if available.
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Proof of purity, either mass spectrometry or chromatographic analysis.
Sample Guidelines
If you have chosen to include gel electrophoresis as the last step in your procedure, it is strongly recommended that you read carefully the article by Hunkapillar, M.W., et al., Isolation of Microgram Quantities of Proteins from Polyacrylamide Gels for Amino Acid Sequence Analysis, Methods Enzymol., 91, p227-236 (1983). Use only those sources for reagents that are listed in these articles unless you have convincing evidence that other sources are superior. Include free radical scavengers to the reservoir buffer such as thioglycolate (1.0 mM). If you stain with Coomassie Blue, be certain to make it a quick stain of 1-2 minutes with as short a destain as possible. We recommend Ponceau S as a stain because it does not require a destaining procedure.
Use only highly purified chemical sources. To avoid free radical blockage on N-termini, gels should be cast one day in advance and stored at 4deg. C. Use minigels to keep the protein/gel ratio high.
