In the quantitative proteomics research, several MS-based methodologies for relative quantification have been introduced for comparison of different proteomes from collected biological samples. Meanwhile, MS-based methods for absolute quantification of specific proteins have been developed to accurately determine the protein concentrations. According to the guidelines for bioanalytical methods, the establishment and validation of accurate analytic proposals require standard compounds of high purity for calibrating and quality controls. Currently, the dominant quantitative strategy is usually a combination of shotgun method and isotope dilution strategy. The targeted proteins in the complicated biological samples would release free peptide fragments induced by specific enzymatic cleavage, and the stable peptides with unique primary sequences in the digest mixture would be utilized as surrogates for corresponding parent proteins, so the small-molecular peptides can be quantified to estimate the protein concentration.
Scientists at Creative Proteomics specialized in the custom synthesis of synthetic peptides and peptide based molecules, providing a confidential and efficient service at competitive prices.
The peptide synthesis service we offer includes:
| Modification List | ||
|---|---|---|
| Modification | Fluorescence/DyeLabeling | D-amino acids & etc |
| Acetylation (N-Terminal) | Biotin (N-Terminal,Y/NAhx) | D-Arg,D-Cys,D-Asp,D-Asn,D-Glu,D-Gln,D-Ser,D-His,D-Thr,D-Trp |
| D-Lys,D-Tyr,D-Orn,Orn,Abu,Aib, (D)1-Nal, (D)2-Pal | ||
| (D)4-Cl-Phe,Nva,Nle,Hse,Hcy,Pen,Mpa | ||
| Acetylation (Lys) | Biotin/FITC (Lysinsequence) | D-Ala,D-Leu,D-Met,D-Pro,D-Val,D-Phe,b-Ala, pGlu, Hyp |
| Formylation (N-Terminal) | FITC/5-FAM (N-Terminal,Y/NAhx) | D-Ile |
| Fatty acid (N-Terminal) | Dansyl (N-Terminal,Y/NAhx) | Gamma-Glu, beta-Asp |
| Myristicacid (N-Terminal) | MCA (N-Terminal) | Dinitrobenzoylation (Lys) |
| Palmytolyl (N-Terminal) | HYNIC (N-Terminal) | |
| Cys(Acm), Cys(tBu) | DTPA (N-Terminal) | Ser (octanoicacid) |
| Benzyloxycarbonylation (CBZ) | ||
| Amidation (C-Terminal) | ||
| p-Nitroanilide (pNA,C-Terminal) | ||
| AMC (C-Terminal) | ||
| Succinylation (Suc,N-Terminal) | ||
| Carbamidomethylated | ||
| Cyclic peptide | Quenched fluorescent peptide | Multiple Antigenic Peptide (MAP) |
| Disulfidebridge1st | Abz/Tyr (3-NO2) | Asymmetric 4 branches |
| Amidecyclic (Sidechain,end) | DABCYL | Asymmetric 8 branches |
| Glu (EDANS) | Crude peptide with HPLC analysis, AAA need toadd extra cost | |
| KLH | ||
| BSA, and etc | ||
| Hydrophobic sequence peptides | Phosphorylation (Tyr,Ser,Thr) peptides | Methylated peptides |
| Tyr,Ser,Thr | ||
| Stable isotope labelled peptides | Difficult sequences/Long Peptide Synthesis | Other Peptide |
| I,A,V,R,K,F,G,L, etc. | N-Methylamino acid (Ala,Phe,Leu,Ile,Val,Gly,Met) & More. | |
Synthetic methods used in Creative Proteomics:
Fmoc and Boc methodologies are both employed, using solid and solution phase reactions. Boc-chemistry solid phase peptide synthesis allows us to synthesise difficult sequences, and gives a greater flexibility in the synthesis of modified peptides. Fmoc chemistry is most suitable for simple peptides and sequences prone to oxidation.
Quality assurance files supplied after synthetic:
All peptides are supplied with COA, RP-HPLC and Mass Spec data. CHN analysis (available, will be online soon), amino acid analysis and N-terminal sequencing can be supplied at an extra cost. View example data: COA, RP-HPLC and Mass Spec.
What purity should I order?
• The most common MS grade purity requested is >95%;
• Antibody production >85% purity is often sufficient;
• NMR and Crystallography >98% is recommended;
• Crude peptides (>50%) can be used for screening large numbers of peptides.
• Any other purity requirement, PLEASE FEEL FREE TO CONTACT US!
How to place an order:
*If your organization requires signing of a confidentiality agreement, please contact us by email
Regarding its success in MS-based quantification of small molecules, the isotope dilution strategy has been recognized as the reference method for internal standardization, introduced into protein quantification with unique advantages over conventional ligand binding assay. In these approaches, the sample is spiked with defined amounts of stable isotope-labeled analogue(s) of unique peptides (AQUA strategy) or intact target protein(s) (PSAQ strategy), to establish the calibrating curves. The mass spec standards of high purity, no matter AQUA peptides or PSAQ proteins, Creative Proteomics can help to synthesize it, to promote your research.
If the target proteins are endogenous ones for the organism and it’s not easy to obtain the blank matrix to prepare calibrating samples, only stable isotope labeled peptides or proteins, especially at the backbone of arginine and lysine, work well in the absolute quantitative proteomics. If the targeted proteins are exogenous for the organism, such as protein therapeutics, and collected blank matrix is available, naive peptides/proteins of high purity can be also used for reference standards without any isotope labeling. For both labeled and non-labeled forms, the experienced professionals can provide solid phase peptide synthesis service for peptides, and intact proteins by proper biosynthesis, folding and modifications with host cells. For SIL peptides/proteins, the products from Creative Proteomics are not only highly pure, but also synthesized with high isotope incorporation, for excellent MS analysis. Contact Us for all the detailed informations!!