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• FREQUENTLY ASKED QUESTIONS
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• Mass Mapping
- Turn-around time?
- In what form should samples be submitted?
- How much sample do you need for the analysis?
- What is the difference between Mass Spec and Mass Mapping?
- Can you digest using enzymes other than trypsin?
- The protein I want to map is a construct created in my lab. Can you still analyze it?
• Protein (Edman) Sequencing
- Turn-around time?
- In what form should samples be submitted?
- How much sample do you need for the analysis?
• Mass Mapping
- Turn-around time? (top)
One week for samples submitted by members of the Stanford community; two weeks or longer for off campus clients.
- In what form should samples be submitted? (top)
Most clients submit samples in SDS-PAGE gels, representing a single, well-resolved band. However, protein in a dried form, or in solution can also be analyzed. Unless submitted in an SDS-PAGE gel, you must provide us with a complete list of ALL components of your sample (buffers, solvents, solutes, etc.) before we will undertake it’s analysis.
- How much sample do you need for the analysis? (top)
We recommend 100 femtomoles for proteins in a gel. Proteins in solution may be identified at a level as low as 10 fmols.
- What is the difference between Mass Spec and Mass Mapping? (top)
When you submit a protein or peptide for mass spectrometry, you are trying to determine an accurate molecular weight; with mass mapping you are trying to identify an unknown protein.
- Can you digest using enzymes other than trypsin? (top)
Trypsin is the ideal enzyme for mass mapping but, for an additional charge we will attempt to map your sample with any of a variety of alternative enzymes.
- The protein I want to map is a construct created in my lab. Can you still analyze it? (top)
Yes, provided that you submit the full amino acid sequence of the construct in single-letter format, we can introduce that sequence into a large database for the analysis. An additional charge will be applied.
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• Protein (Edman) Sequencing
- Turn-around time? (top)
One week for samples submitted by members of the Stanford community; two weeks or longer for off campus clients.
- In what form should samples be submitted? (top)
Best is adsorbed to PVDF membrane, usually following blotting from an SDS-PAGE gel. Only PVDF can be used. Nitrocellulose, for example, is absolutely forbidden. Alternatively, protein/peptides can be submitted as a dry powder, such as synthetic peptides, or in solution. Unless adsorbed to PVDF membrane, you must provide us with a complete list of ALL components of your sample (buffers, solvents, solutes, etc.) before we will undertake it’s analysis.
- How much sample do you need for the analysis? (top)
Blotted samples should contain 100 pmol of protein. Proteins or peptides dried or in solution may be identified at a level as low as 5 pmol.
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