Synthesized peptides are offered in different amounts and different purity grade according customer needs. Whatever the scale of synthesis chosen, the customers are guaranteed of receiving high quality peptides: the chemical structure of each peptide is determined by MALDI-TOF mass spectrometry analysis and the purity is certificated by HPLC chromatograms.

-Very fast delivery is guaranteed all over the word by rapid production and by express carrier shipping of the vials containing the lyophilized product.

-We maintain absolute confidentiality. If required, we will be pleased to sign a secrecy agreement before receiving your peptide structure.

-In addition to standard custom peptide synthesis service, a large array of peptide modifications is offered for a variety of applications, according to individual needs.

Peptide labelling and modifications

We can introduce modifications at any suitable position of your peptide.

Peptide modifications:

· N-terminal acetylation (free)

· C-terminal amidation (free)

· Biotinylation.

· Linkers: Aminohexanoic Acid, 8-Amino-3,6-dioxaoctanoic Acid.

· Phosphorylated amino acids (phosphoSer, phosphoThr, phosphoTyr).

· D-amino acids.

· Methylated peptides: Lys(Me), Lys(Me)₂, Lys(Me)₃, Arg(Me)₂ symmetrical, Arg(Me)₂ asymmetrical.

· Na-Methylated.

· Ca-Methylated.

· Formylation.

· Bromoacetylation.

· Myristoylation.

· Succinylation.

· Cyclic peptides: Lactam (amide bond formation), Disulfide (S-S bond formation).

· 2/4 branched MAPS.

Conjugated peptides:

· Conjugation with carrier protein (e.g. OVA, KLH or BSA).

Peptide labelling

We can introduce either at the N-terminus or at the side chain of Lysine residues wherever along the sequence:

· Chromogenic probes:
Red region of the spectrum (e.g Lissamine, 5(6)-carboxytetramethyl rhodamine [5(6)-TAMRA] )
Green region of the spectrum (e.g 5(6)-carboxyfluorescein [5(6)-FAM], 5 carboxy fluorescein [5-FAM], 4-chloro-7-nitrobenzofuran [NBD] ).

Blue region of the spectrum (e.g. 5-(dimethylamino)-1-naphtalenesulfonyl [DNS])

· FRET probes:
fluorophores: MCA, Lys(MCA), Glu(EDANS)
quencers: DABCYL, Lys(DABCYL), DNP, Lys(DNP)

Metal chelators for “in vivo” imaging:

· DOTA, DTPA and DTPAGlu (at the N-terminus).

· Lys(DOTA) (wherever along the sequence).

Stable Isotopes for biomolecular NMR:

As an example:

· Gly (G) (¹⁵N) labeled on alfa Nitrogen atom.

· Gly (G) (1-¹³C) labeled on alfa Carbon atom.

· Gly (G) (U-¹³C2; ¹⁵N)  labeled on all Carbon and Nitrogen atoms.

Peptide libraries

Peptide libraries have become an essential tool to cope with the fast-growing field of proteomics.

Peptide libraries enable the highly efficient and cost effective screening of a large number of molecules in a variety of areas of biomedical interest: drug discovery, GPCR ligand screening, protein-protein interaction, functional proteome, nucleic acid binding, enzyme substrate or inhibitor screening, antigen and epitope screening, discovery of signal molecules, peptide/protein cross talking, etc.

Custom peptide libraries are provided of any size and purity (crude, >70%, >80%, >95%) to meet the most stringent requirements of your screening assays:

• Mapping of immunodominant regions in antigens
• Identification of substrates for orphan enzymes
• Optimization of known enzyme substrates
• Elucidation of signal transduction pathways
• Characterization of protein-protein contact sites
• Detection of potential phosphorylation sites in kinase substrate proteins
• identification of phosphatase substrates and profiling of phosphatase substrate specificities
  
  

In addition to Libraries of standard peptides ProtEra offers also:

-Libraries of peptides with N-terminal:

· Biotinylation.

· Fluorescinylation.

· Formylation.

· Bromoacetylation.

· Myristoylation.

· Succinylation.

-Libraries of phospho-peptides.

Peptides are delivered as lyophilised products in individual labelled tubes with complete QC data including Certificate of Analysis, RP-HPLC, and MS.

To follow few examples on the generation of peptide libraries:

Overlapping peptide library

An overlapping peptide library is generated for epitope mapping. Characterized by two parameters, fragment length and offset number, each library is generated by breaking the original protein or peptide into many equal-length overlapping fragments. As a general guideline, a peptide fragment should be at least 6 residues in length for it to cover an epitope and should not exceed the 15-20 residues in length to limit synthetic and purification complexity. The offset number is the number of amino acid residues shifted between adjacent fragments and it reflects the degree of overlap. The suggested offset number is 3-5 residues. From experience, the combination of low offset number and medium size fragments (12-15 residues in length) grants the obtainment of the most reliable information.

Truncation library

A truncation library allows the definition of the minimum length required for peptide’s activity. The library is generated through a systematic truncation of the peptide's sequence from each terminus. In many cases, truncation library screening gives knowledge about the peptides with enhanced proteolytic stability.

Alanine scanning library

Alanine scanning library is generated to identify specific amino acid residues responsible for the peptide’s function, stability, and conformation. Alanine, the smallest chiral amino acid, is used to substitute each non-alanine residue one at a time. Substitution of key amino acid residue(s) with alanine causes diminished epitope activity.

Positional scanning library

Positional scanning library is an important tool for peptide sequence optimization. It identifies amino acids of interest at a given position or positions and substitutes the amino acid(s) at that position with all other natural amino acids one at a time. It generates high value data by locating potential more favorable residue(s) at specified position(s) for enhanced peptide activity.

Random library

Random library is an indispensable tool for sequence optimization. It generates alternative peptides that could have the potential for enhanced activity. Selected residues are randomly and simultaneously substituted with all other 20 natural amino acids.