Research and Development

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Tel: +44 (0)1223 260008, e-mail: info@activotec.com or fill out our enquiry form

Activotec has an extensive R & D programme based on the modification and production of peptides and proteins for therapeutic use.

N- to C- Directed Solid-Phase Peptide Synthesis

Solid phase peptide synthesis from N-to-C direction was developed in the early nineties in Southampton, UK [Sharma, Patent WO 90/05738]. The alkoxysilyl moiety was used as a temporary carboxyl protecting group. Using this novel N-to-C methodology a number of peptides have been synthesised. This N to C method is disclosed in Sharma, R. P., Jones, D. A., Corina, D. L. and Akhtar, M. (1994) in Peptides: Chemistry, Structure and Biology, Proceedings of the Thirteenth American Peptide Symposium (Hodges, R. S. and Smith, J. A., eds.), pp. 127-129, ESCOM, Leiden, , Jones, D. A. (1993) PhD Thesis, University of Southampton.

The important advantage of this strategy is that it allows the preparation of peptide analogues possessing C-terminal modifications (such as esters, thioesters, alcohols and aldehydes) and peptides possessing peptide bond modifications (such as reduced peptide bonds, urea and isosteres) on the solid phase which has important applications in the synthesis of peptides of therapeutic interest e.g. a-MAPI [Sharma, Chem. Commun., 1998, 1449-1450]

First efficient synthesis of a-MAPI (download the article as a PDF file)

The methodology has been extensively scrutinized for any racemisation produced during peptide synthesis on the solid-phase by using both physical (specific optical rotation, RP-HPLC analysis) and chemical (enzymatic studies) methods. No detectable racemisation has been observed for the synthesis of peptides during N-to-C synthesis. The method is simple, mild and amenable to automation [Anja Johansson J. Comb. Chem. 2000, 2, 496-507]

Solid-phase Ligation

Protein therapeutics has emerged as one of the most promising segments of the pharmaceutical market since the introduction of recombinant insulin in 1982. To produce these important drugs commercially, companies have focused to date on biological approaches such as recombinant DNA expression methods (microbial fermentation and mammalian cell culture) and native protein isolation. However numerous problems are associated with these methods:

• limited supply of product is possible
• viral contamination risk
• product heterogeneity
• inability to produce some proteins e.g. those that are toxic to the cell
• non-human post-translational modifications, i.e. incorrect glycosylation or folding
• time-consuming
• structural modifications are limited to the 20 naturally occurring amino acids.

Protein-based drugs represent one of the largest pharmaceutical markets with several blockbuster drugs in existence (e.g. EPO at 6.8Bn). Although there is the potential for numerous others, these drugs are expensive to produce, and can contain biological contaminants that give rise to serious side effects. Activotec is developing a novel method for the de novo synthesis of therapeutic proteins to chemical standards of purity not attainable by recombinant means.

In particular the company is developing an efficient ligation approach in which two peptide fragments are coupled while still attached to the solid-phase. By synthesising one fragment in the N- to C- direction and one in the C- to N- direction, facile coupling of the exposed C- terminus and N- terminus occurs, generating a natural peptide bond. This process can be repeated sequentially until the desired target protein is made.

This approach has been further extended by using soluble supports, such as polyethylene glycol, to allow economic synthesis of commercially important therapeutic proteins/peptides.

Synthesis of modified proteins

N- to C- synthesis has been utilised to create amino acid analogues in which the carboxyl group is replaced with a diol functionality. This group acts as unique masking group for the sequential ligation of peptide fragments, for the synthesis of artificial proteins, and in the generation of peptide-aldehydes, an important class of peptide/protein therapeutics. Other potential applications include protease resistance, drug delivery tools, vaccine design and peptide-drug conjugates.

In June 2005 Activotec was privileged to receive a BBSRC research grant of £160,000 over two years. We will develop a novel method for the de novo synthesis of therapeutic proteins to chemical standards of purity not attainable by recombinant means. It will employ polyethylene glycol as a temporary solubilising agent in the sequential chemical ligation of synthetic peptide fragments to allow the economic synthesis of commercially important therapeutic proteins/peptides (calcitonin, exenatide, beta-amyloid, eotaxin, GM-CSF, and IL-2).

Intellectual Property

Activotec has filed a number of patent applications based on the above technology. Further patents have been filed relating to the development of novel peptide-based products for the treatment of cancer, HIV and diabetes.

For further information please contact Chris Littlewood on +44 1223 260008 or e-mail: General web site enquiry