Protein Identification

There are two methods offered for protein identification; peptide mass fingerprinting by Maldi-Tof and sequencing by ESI/MS/MS. Both methods require that the protein to be identified be in a public domain database, or if the sequence is know and you wish to confirm the identity, you may also sendus your proprietary sequences.



The success rate for the identification of proteins is higher by ESI/MS/MS than by Maldi-Tof. Positive identification by Maldi-Tof requires that a number of peptides "fly" for an accurate identification and that these peptide be not post-translationally modified. In the case of ESI/MS/MS as long as a single peptide "flies" and that it can be sequenced the identification rate is high.



To minimise costs we propose a two-step invoicing stucture

all sample treated are invoiced a setup fee, those samples which are identified with a high score as also invoiced a success fee. If we do not identify your protein, only the setup fee will be invoiced.

Description	Reference	EUR
MALDI Protein identification Setup Fee for MALDI peptide mass fingerprinting protein identification, includes sample preparation, tryptic digest, desalting.	MS-MALD-SETUP	155.00
Protein identification Success Fee by MALDI peptide mass fingerprinting, includes sample preparation, data acquisition and database search, raw data and results, does not include setup fee	MS-MALD-PROTID	133.00
ESI/MS/MS Protein identification Setup Fee for ESI/MS/MS protein identification, includes sample preparation, tryptic digest	MS-ESI-SETUP	155.00
Protein identification Success Fee by ESI/MS/MS de novo sequencing, includes sample preparation, peptide separation, data acquisition and database search, raw data and results, does not include setup fee	MS-ESI-PROTID	195.00

Maldi-Tof

This method involves the analysis of a previously purified protein (1D, 2D gel spot or HPLC fraction) by Mass Spectrometry with the goal of matching the protein sample’s peptide signature to a database. The process involves the digestion of the protein sample with trypsin, producing peptide fragments. The mass list of these peptide fragments is unique for different proteins. This list is compared to protein databases for which theoretical digest fragments have been calculated to identify the protein sample. Detection down to 10’s of femtomoles is possible with this technique however success is dependent on the purity of the protein, compatibility of the protein source with the databases searched as well as the comprehensiveness of the databases. Factors that can lead to unsuccessful results include post-translational modifications, insufficient protein sample and sample contamination. Contact us for specifics about your protein sample.

Maldi-Tof Sample requirements.  

We request 100 femtomoles, (e.g. a visible Coomassie stained spot), of material for peptide fingerprinting analysis. Samples may arrive as frozen solutions on dry ice, or lyophilized protein, gel plugs, or complete gels for spot picking. Keratin contamination must be avoided by working under clean bench conditions. Samples submitted as cut gel spots should be stored in an labeled Eppendorf tube, sealed with Parafilm and shipped at room temperature. After reception of the samples, you will receive an acknowledgment of receipt, indicating a project number that you can refer to for any further discussion which may arise. 

ESI/MS/MS

Protein sequencing with ESI/MS/MS involves the analysis of a previously purified protein (1D or 2D gel spot) by firstly subjecting the protein to an enzymatic digest, purifying the peptides by nano-capillary HPLC, analysing each peptide mass as they elute from the HPLC column, and refragmenting each peptide into amino acid fragments. From these fragments the sequence can be reconstructed and determined. Sequence information is then compared to databases for identification. Up to 10 amino acid sequence information can be determined per peptide with this method. Detection down to 100’s of femtomoles is possible with this technique however success is dependent on the purity of the protein, compatibility of the protein source and the databases searched as well as the comprehensiveness of the databases. This method does not distinguish between leucine and isoleucine and only difficultly between lysine and glutamine. Contact us for specifics about your protein sample.

ESI/MS/MS Sample requirements.  

Sample requirement for analysis: 500 femtomoles (e. g. a dark Coomassie stained spot). Samples may arrive as frozen solutions, lyophilized protein, gel plugs, or complete gels for spot picking. Keratin contamination must be avoided by working under clean bench conditions. After reception of the samples, you will receive an acknowledgment of receipt, indicating a project number that you can refer to for any further discussion which may arise. 

Please provide all of the following information so that we may begin to process your order

 

				• Peptide sequence for anti-peptide programmes • Purchase order number from your institute • Product references and prices • Other important production information
				Delivery information • Name • Shipping Address • Telephone • Email	Invoicing information • Name • Shipping Address • Telephone • Email

• Online
  You can place your order online. Login to access our web ordering interface.

• By e-mail: order@eurogentec.com

• By fax : +32 4 264 07 88

• By mail
  Eurogentec S.A.
  LIEGE Science Park
  Rue du Bois Saint Jean 5
  4102 Seraing
  BELGIUM

If you still have questions with ordering please contact our Customer Support : +32 4 372 76 65.