PePro

Abpro is a full service provider of anything you need to make an antibody including antigen design, synthesis and conjugation.  Our experienced scientists use state-of-the-art software to design peptide antigens.  We call our proprietary software the PePro^TM Antigen Design System.

 

We are so successful that we are able to guarantee the effectiveness of our antigens.

 

• We guarantee a minimum of a 1:15,000 ELISA titer for polyclonal antibodies on any sequence that we design or your money back.

 

• We guarantee at least one hybridoma specific to any peptide we design.  If we cannot deliver at least one clone producing specific antibody, you will not be charged for the project.  

 

• Maximized antigenicity

• Avoid epitopes which are conserved in native protein structure

• Optimize sequence length

• Ability to specify desired cross reactivity

• Guaranteed immune response

 

Peptide antigens must be:

• Antigenic

• Immunogenic

• Properly sized

 

We utilize the Kolaskar and Tongaonkar antigenic scale, an algorithm designed to predict the exposed epitopes on the surface of a protein.  This is a semi-empirical method which makes use of physicochemical properties of amino acid residues and their frequencies of occurrence in experimentally known segmental epitopes.  It was developed to predict antigenic determinants on proteins. Application of this method to a large number of proteins has been shown to predict antigenic determinants better than other known methods.

 

Because of their size most peptides are often not immunogenic on their own.  The peptides serve as epitopes when coupled to carriers (BSA & KLH) capable of generating an immune response.  Peptide-carrier conjugates seldom fail to elicit a response because of tolerance.  Consequently, the peptides can usually be seen as epitopes and high-titer  antisera can typically prepared.  We select peptides which have low homology with the host immunized and present minimum coverage with other potential epitopes.  This selection is made through successive rounds of BLAST searches of the peptide against the host genome and the human non-redundant set.

 

Although there are exceptions, peptides smaller than 6 residues in length typically generate a weak immune response.  Synthesis of peptides longer than 20 residues often produces side reactions making it increasingly difficult to purify a single peptide product.   In addition, longer peptides are more likely to contain residues that make coupling to carrier molecules more difficult.  The safest choice is the generation of multiple peptides 10-15 residues in length covering the region to be targeted.

 

Once a sequence of the protein has been established as antigenic and immunogenic, the peptide sequence is screened for certain amino acids which have to be avoided:    

• Peptides containing (>1): Cysteines (Cys, C), Methionine (Met, M), Arginine (Arg, R) and Tryptophan (Trp, W).

• Peptides containing Glutamine (Gln, Q) and Asparagine (Asn, N) or their acids versions: Glutamic acid (Glu, E) and Aspartic acid (Asp, D).

• Peptides containing C-terminal Proline (Pro, P).

• Peptides greater than 20 amino acid residues.

 

Once PeProTM produces a sequence, our Ph.D. immunologists and biochemists review the peptide to ensure that it is the best possible antigen, then begin synthesis.