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Mass spectrometry can be routine, but when dealing with research samples it rarely is.
The most important question when bringing a sample to us is, “What do you want to know about this sample?”
If you need the accurate molecular weight of a protein, we will need about 5-10 μg of protein, preferably in solution at ≥0.5 mg/mL. The solution should not contain any large detergents such as SDS or Triton (=NP-40). Our measurements are frequently accurate to ±1 Da for proteins with MW < ~40 kDa. Proteins with MWs > 100 kDa rarely run successfully.
If your sample is a protein in solution and you want us to identify it, we will need 20-40 μL of a >0.1 mg/mL solution. The solution should not contain any large detergents, such as SDS, Triton or NP-40. (We may have alternate solutions if these seem to be essential.) Salts, buffers and glycerol are OK. Discuss the sample composition with us before sending a sample.
If your sample is a protein gel band or spot and you want us to identify it, there are several issues. We use a sequential approach in doing these identifications, that is, we do the easiest thing first, then more difficult ones if necessary. If your protein is likely to be in a database we can use the easier approaches, so we need to know your best guess about whether your protein primary sequence might be found in one of the public databases. We also need to know the origin and approximate MW (from the gel) of your protein. Some additional factors to be aware of in preparing the gel sample are listed below.
If you want to cut out and digest the sample yourself, we can provide you the procedures (See In-gel digestion procedure). If you have just a few samples, it’s probably not worth it for you to set up to do this, but if you have many samples, the work will go much faster if you do this part yourself.
Identifying post-translational modifications is never routine. Please speak with us before embarking on this endeavor.