Peptide Design
GenScript's Antigen Design Tool incorporates some of the most advanced algorithms in the industry. The design process takes into account all critical factors, including peptide solubility, length, and antigenicity. Each peptide is screened against a specific protein databank to limit cross-reactivity and improve overall antibody specificity. The success rate of GenScript's peptide synthesis, regarding peptides designed, synthesized, and conjugated using GenScript's FlexPeptideTM technology, is as high as 85-90% when measured by in the production of immunoresponsive antibodies.
Below are some key factors that GenScript takes into account in designing peptides:
Amino Acid Composition
Amino acid composition affects peptide assembly, solubility, stability, and the purification process. Most peptides of biological interest, such as peptide antigens, are usually derived from the N-terminal, C-terminal, or internal sequences of native proteins. However, these peptides, in their native forms, are not always ideal for research purposes. Some may be insoluble or unstable, while others may be difficult to purify or improperly folded.
GenScript's veteran experts can pinpoint potentially problematic amino acids and modify them to improve peptide assembly, solubility, stability, and antigenicity. Our modification methods include capping of the N- and C-termini, chemical modifications, spacer insertions, and amino acid replacement, all tailored to the source of the sequence and the intended application.
Length of Sequence
The length of the peptide is one of the critical factors that must be considered in peptide synthesis. The longer the peptide sequence, the more difficult its synthesis and purification. GenScript synthesizes peptides using both solid and solution phase methods. For long and complex peptides, GenScript has developed a proprietary recombinant peptide system.
GenScript recommends peptides of 10-15 residues for the production of antibodies meant to respond to the linear epitopes of intact proteins.
Hydrophobic Stretches
Hydrophobicity strongly influences peptide solubility, a fact of which GenScript's peptide design technology takes full advantage. GenScript's peptide design technology can improve and increase peptide solubility by changing the frequency of hydrophobic and hydrophilic amino acids. Peptides with high incidences of tryptophan, leucine, valine, methionine, phenylalanine, and isoleucine may not dissolve in aqueous solutions. It is usually advisable to keep the hydrophobic amino acid content below 50% and to make sure that there is at least one charged residue for every five amino acids. At physiological pH, arginine, glutamine, aspartic acid, and lysine all have charged side chains. A single conservative replacement or the addition of a set of polar residues to the N- or C-terminus may also improve solubility.
Difficult Amino Acids
Cysteine, methionine, and tryptophan residues are susceptible to oxidation and side reactions. Peptides containing multiple instances of these residues are also difficult to obtain in high purity. GenScript's peptide design technology can manage these difficult amino acids to avoid peptide oxidation and ensure peptide purity.
Secondary Structure
During peptide synthesis, beta sheet formation can cause incomplete solvation of the growing peptide, which results in a high incidence of deletion sequences in the final product. GenScript peptide design technology effectively reduces these unwanted byproducts, thereby increasing peptide yield, quality, and purity. In general, GenScript recommends that sequences not contain multiple or adjacent residues of valine, isoleucine, tyrosine, phenylalanine, tryptophan, leucine, glutamine, or threonine. In such cases, conservative replacements and other measures may help break the pattern and improve final peptide quality. Such measures include inserting a glycine or proline at every third residue, replacing glutamine with asparagine, or replacing threonine with serine.
Delivery Specifications:
All peptide synthesis is subject to GenScript's stringent quality control. The typical delivery consists of lyophilized peptide of the required sequence, purity, and quantity and associated QC reports.
Quotations and Ordering:
 For quotations, please use our Instant Online Quotation/Order system. However, you may also contact us by email, phone (1-732-885-9188), fax (1-732-210-0262), or via our secure messaging system.
Please use our online ordering system and either a PO (Purchase Order) or credit card to receive GenScript's fastest service. For batch order, please download and complete Standard Peptide Batch Order Form and email it to peptide@genscript.com. Our customer service representatives are available 24 hours, Monday through Friday to assist you.
We accept POs and major credit cards ( ). A 7% New Jersey sales tax will be applied to orders shipped to New Jersey. Your credit card will be billed under "GenScript Corp." Click here to download our credit reference form. For international orders, we must apply the full charge at the time the order is placed. In the unlikely event that any given order cannot be filled, our guarantee will take the form of a full refund.
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