FAQ

Proteomic FAQ

How should I prepare gel samples for protein ID?

  1. Gel Running

    We accept gel spots/bands from all types of SDS-PAGE gels and 2D gels. Users should pay special attention to reduce contamination, such as keratin. Always wear gloves when handling gels and wash apparatus thoroughly. It is advised to use fresh sample loading buffer, running buffer, fixing and staining solutions with clean DI water.

  2. Gel Staining

    Coomassie blue based staining (traditional, Colloidal blue, SimplyBlue, etc.) and fluorescent dye staining (such as Molecular Probes' SYPRO Ruby staining) are all compatible to mass spec based protein ID.

    Silver staining is also acceptable as long as you use mass spectrometry compatible protocols. We generally find good results using PIERCE Silver SNAP or Invitrogen silver stain kit. Please note that we found de-staining is not necessary and may have negative effect on mass spectrometry results. We also noticed that the developing step of the staining procedure is critical. Please stop the developing reaction the moment your band is visible. It is not advised to develop more than 10 min.

  3. Band Cutting

    Take a photograph of the gel before cut it! Once you cut out a band, please mark the position on the photograph. Please submit the picture with your sample. The gel picture will help us in designing the sample loading amount and sequence to avoid carry-over.

    Put the gel on a clean glass plate and cut the bands with sharp razor blades (use new razor blade for each gel band to avoid cross-contamination). Do your best to avoid any direct contact with the gel with bare hands, light box, or any other possible sources of keratin contamination.

    Try to cut out a band as close to your protein as possible. Higher protein/gel ratio ensures more efficient peptide extraction, higher MS detection sensitivity, therefore better protein ID results.

    Put each gel band in a clean, 0.5 or 1.5 ml micro-centrifuge tube, and label each tube carefully. Follow our sample submission procedure to submit your samples.

    Duplicate samples are always welcome although generally not necessary. They will be used as backup and will not be double-charged.

How should I stain my gel?

We can work on gels stained in many ways, including commassie blue-based staining (traditional commassie blue, Colloidal blue, and SimplyBlue, etc.), fluorescent dye staining (such as Molecular Probes' SYPRO Ruby staining), and sliver staining.

For silver staining, we have found that a lot of commercially available kits work quite well, such as PIERCE Silver SNAP, Invitrogen silver stain, and Bio-Rad Dodeca Silver Stain. Be sure to check the product brochure or call their technical support to make sure that the silver stain method you use is mass spec compatible. Develop the staining to the minimum in order to maximize the chance of identification by mass spec.

All gels, no matter what stain you use, have to be fixed. This step is generally included in the protocol or combined with staining steps in most commercially available kits and methods. For some staining procedures, such as Zn stain, no fixation step is included. In that case, once the band is cut, it should be fixed in the tube with 10% acetic acid and 40% ethanol for 1 hour.

How to submit my samples?

Thanks for your interest in our business! Please follow the simple directions below to submit your samples. Remember, if you have any questions or concerns before, during, or after the submission, please feel free to contact our technical support. We also encourage you to contact us for a free consultation on your project if you are not sure whether our service can help you.

First, from our Catalog, choose Services, and then choose the service you would like. After telling us the detail of your samples, you then click Add to cart. Follow directions to checkout, review, and submit your order. An invoice will be send to your registered email account. Please click the Print icon on the top of the invoice to print out your invoice and attach it to your actual shipment in the next step. You will be asked to log in or register a new account as a first time user during checkout. Please keep the user name and password in a safe place so that you can check the status of your order online. You also need your account for future orders and check your order history.

Second, ship the samples AS WELL AS your invoice printout from above step. For protein ID project, in general gel samples may be shipped at room temperature via any express service from either a shipping company or US postal office. A good practice is to pack these microtubes (each tube contains one gel band) in a 50 ml centrifuge tubes. Use KimWipes to occupy any empty room if the 50 ml tube is not full and cap it tightly. Any shipment should contain a copy of invoice printout and a gel picture labeled with each target band labeled.

All solution samples must be shipped in a dry ice container with express service.

Now, just relax and your protein ID results will be in your email within about one week after we receive your samples. Again, please feel free to contact our technical support for any questions and concerns.

How should I store the gel bands before sending them to you?

We recommend that you ship the gel bands at your earliest convenience once they are cut out. However, gel bands are quite stable and they can be stored in 4 °C or -20 °C for about a week without any negative effect on protein ID results.

What is your general protein ID procedure once you receive my samples?

Our protein ID procedure is the following:

  1. In-gel Digestion
    1D gel bands or 2D gel spots are processed for in-gel trypsin digestion. The resulted tryptic peptides are extracted, dried down, and re-suspended for LC-MS/MS analysis.
  2. LC-MS/MS Analysis
    Tryptic peptides from the above step are run on a nano HPLC with a 75 μM ID reverse phase column, which is connected to a Thermo LTQ ion trap mass spectrometer. Data from a run of 45 minutes will be collected and used for protein database search.
  3. Protein Database Search
    LC-MS/MS data are searched against protein databases such as NCBI or SwissProt. A protein hit list will be generated.
  4. Manual Validation
    The initial hit list will be manually examined by our scientists to eliminate any false positives based on LC-MS/MS raw data, bioinformatics analysis, and sample information. We only provide protein ID with high confidence level.
  5. Report
    A Protein ID Report with a list of all identified proteins is delivered to customer by email.

I wanted to identify a protein in my gel band, but I got 10 proteins identified. How is that possible?

The reason for multiple protein IDs is the superior sensitivity of our instruments. A single band from 1D gel may well contain 30 proteins and a single 2D spot can have up to 5 proteins.

There are too many proteins identified in each sample. How should I analyze them?

We are happy to help you! Please let us know how you want to analyze your samples. For example, do you want to find proteins that only exist in sample A, but not in sample B? Or do you only care about major protein components? Please describe your needs in the comment area during sample submission or contact us later. We can generate a report that specifically addresses your questions and is easy for you to understand.

I only care about the major protein that contributes to the uniqueness of the band, compared to the control sample. Can you tell me which is the major protein?

It is usually not too difficult to tell a major component from proteins in trace amount. If you find one or two proteins that have significantly higher log(e) number, it normally means that they are major components. However, we generally try to present data in an objective way to a customer and let the customer make decisions about the results. We will answer any questions regarding the results upon customer request.

Customers are strongly encouraged to discuss with us if further actions will be taken based on the MS results, such as making a knock out strain or generating/purchasing an specific antibody.

Can you tell me the percentage of each protein component in my sample?

We can only offer an estimated percentage based on information from all proteins identified. In general it is not recommended to use these data in statistical analysis.

Why are keratins identified in my sample?

Keratins are ubiquitous in the air, water, glassware, and solutions. We have found that keratins are more prominent when protein concentration in a sample is extremely low.

Some precautions will help reduce keratin contamination, such as wearing gloves, rinsing glassware, and making fresh solutions. However, we have not found keratin to be serious threat to our protein identification.

Do you work on solution samples?

Absolutely. Just let us know the experiment purpose, the solution contents (such as buffer conditions, whether or not you have detergent, concentration of the detergent, estimated protein concentration) and we will design a procedure that best suits your samples. Remember you have to ship any solution samples on dry ice.

General FAQ

What payment methods do you accept and how to make a purchase?

Major Credit Cards

We accept Visa, MasterCard, Discover, and American Express.

Purchase Order

An invoice will be emailed to you after you confirm the order by Purchase Order. FAX your SIGNED Purchase Order AS WELL AS the order invoice to 908-382-3285. Customer is responsible to make full payment within 30 days after receiving the products or services from Optimum Biotech.

Check/Money Order

An invoice will be emailed to you after you confirm the order by Check/Money Order. Please mail your check/money order AS WELL AS the invoice printout to:

Optimum Biotech
14 Concord Lane
Skillman, NJ 08558 USA

Your products or services will be prepared once we receive your check/money order.

Please notice that for international purchases, we only accept bank check or money order in US dollar if you choose to use Check/Money Order as purchase method.

Bank transfer and other methods

If none of the above method works for you, we will try to accommodate you with your preferred methods, such as bank transfer or any other methods. Please feel free to contact us to obtain detailed information.

Do you accept international purchase?

Yes, we ship to many different countries all over the world and you may choose your preferred shipment methods (US Postal Service is much cheaper, and UPS/FedEx is more expensive). Our payment process allows you to make a purchase using most popular credit cards in your country, or you may choose bank transfer or any other methods. Just contact us for more details!