You provide us with: a) or b):

a) Homogenous protein in an excised band from a dried SDS-gel (stained with Coomassie Blue or Silver, preferably without fixation). Please enclose a gel photo. Please mention the %age of the gel, clearly mark the band which was excised from the gel, and specify the molecular weight marker and the estimated molecular weight of the protein of interest.

b) At least 25 µg purified native protein (ammonium sulfate precipitate or lyophilized protein). Please, enclose a photo of an analytical SDS-PAGE, mention the %age of the gel, clearly mark the band which corresponds to the purified protein, and specify the molecular weight marker and the estimated molecular weight of the protein of interest. Recommend a suitable buffer for dialyzing (ammonium sulfate precipitate) or dissolving (lyophilized material) the protein. If this is not a standard buffer, add your buffer in sufficient amount (esp. for dialysis). Mention special requirements of your protein with respect to solubility and stability (especially important for membrane proteins).

Required Information:

Protein identity (incl. database entry number) and source of the protein (organism, tissue, cell type, sub-cellular fraction etc.).

Please ship the protein without cooling (dried gel bands, lyophilized protein) or on blue ice (ammonium sulfate precipitate) to:

Gentaur
Avenue de l'Armée 68/B4
B-1040 Brussels BELGIUM

1. (In gel) trypsination of the protein (band) of interest (protein is cleaved at arg and lys sites into peptides)
2. MALDI-TOF Mass Spectometry analysis of the tryptic peptides
3. Peptides carrying posttranslational modifications are identified by comparing their actual mass with their theoretical mass peak by peak. This process is carried out by experienced scientists. A list of experimental peptides that correspond to unmodified peptides is generated, then a list of experimental peptides that match to peptides which carry modifications of cystein residues, methionine residues, or other modification as documented in SWISS-PROT is created. In order to find novel modifications, the mass differences between all experimental peptides and all theoretical peptides are calculated. If a mass difference corresponds to the mass of any known modification the peptide is classified as potentially modified. Within the peptide the potential amino acid(s) that may carry the modification in question is/are suggested.

Cat. Nr. IPM01: Identification of Posttranslational Protein Modification by MALDI-TOF-MS, protein shipped in protein gel band
Price: 650 Euro

Cat. Nr. IPM02: Identification of Posttranslational Protein Modification by MALDI-TOF-MS, purified protein provided
Price: 720 Euro