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A Native Chemical Ligation Approach for Combinatorial Assembly of Affibody Molecules
KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).ORCID iD: 0000-0002-0695-5188
2012 (English)In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 13, no 7, 1024-1031 p.Article in journal (Refereed) Published
Abstract [en]

Affinity molecules labeled with different reporter groups, such as fluorophores or radionuclides, are valuable research tools used in a variety of applications. One class of engineered affinity proteins is Affibody molecules, which are small (6.5 kDa) proteins that can be produced by solid phase peptide synthesis (SPPS), thereby allowing site-specific incorporation of reporter groups during synthesis. The Affibody molecules are triple-helix proteins composed of a variable part, which gives the protein its binding specificity, and a constant part, which is identical for all Affibody molecules. In the present study, native chemical ligation (NCL) has been applied for combinatorial assembly of Affibody molecules from peptide fragments produced by Fmoc SPPS. The concept is demonstrated for the synthesis of three different Affibody molecules. The cysteine residue introduced at the site of ligation can be used for directed immobilization and does not interfere with the function of the investigated proteins. This strategy combines a high-yield production method with facilitated preparation of proteins with different C-terminal modifications.

Place, publisher, year, edition, pages
2012. Vol. 13, no 7, 1024-1031 p.
Keyword [en]
antibody mimics, biotechnology, chemoselectivity, peptides, solid-phase synthesis
National Category
Biochemistry and Molecular Biology
URN: urn:nbn:se:kth:diva-95231DOI: 10.1002/cbic.201200052ISI: 000303191900014ScopusID: 2-s2.0-84860251745OAI: diva2:528092

QC 20120524

Available from: 2012-05-24 Created: 2012-05-21 Last updated: 2014-02-07Bibliographically approved
In thesis
1. Chemical Engineering of Small Affinity Proteins
Open this publication in new window or tab >>Chemical Engineering of Small Affinity Proteins
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Small robust affinity proteins have shown great potential for use in therapy, in vivo diagnostics, and various biotechnological applications. However, the affinity proteins often need to be modified or functionalized to be successful in many of these applications. The use of chemical synthesis for the production of the proteins can allow for site-directed functionalization not achievable by recombinant routes, including incorporation of unnatural building blocks. This thesis focuses on chemical engineering of Affibody molecules and an albumin binding domain (ABD), which both are three-helix bundle proteins of 58 and 46 amino acids, respectively, possible to synthesize using solid phase peptide synthesis (SPPS).

In the first project, an alternative synthetic route for Affibody molecules using a fragment condensation approach was investigated. This was achieved by using native chemical ligation (NCL) for the condensation reaction, yielding a native peptide bond at the site of ligation. The constant third helix of Affibody molecules enables a combinatorial approach for the preparation of a panel of different Affibody molecules, demonstrated by the synthesis of three different Affibody molecules using the same helix 3 (paper I).

In the next two projects, an Affibody molecule targeting the amyloid-beta peptide, involved in Alzheimer’s disease, was engineered. Initially the N-terminus of the Affibody molecule was shortened resulting in a considerably higher synthetic yield and higher binding affinity to the target peptide (paper II). This improved variant of the Affibody molecule was then further engineered in the next project, where a fluorescently silent variant was developed and successfully used as a tool to lock the amyloid-beta peptide in a β-hairpin conformation during studies of copper binding using fluorescence spectroscopy (paper III).

In the last two projects, synthetic variants of ABD, interesting for use as in vivo half-life extending partners to therapeutic proteins, were engineered. In the first project the possibility to covalently link a bioactive peptide, GLP-1, to the domain was investigated. This was achieved by site-specific thioether bridge-mediated cross-linking of the molecules via a polyethylene glycol (PEG)-based spacer. The conjugate showed retained high binding affinity to human serum albumin (HSA) and a biological activity comparable to a reference GLP-1 peptide (paper IV). In the last project, the possibility to increase the proteolytic stability of ABD through intramolecular cross-linking, to facilitate its use in e.g. oral drug delivery applications, was investigated. A tethered variant of ABD showed increased thermal stability and a considerably higher proteolytic stability towards pepsin, trypsin and chymotrypsin, three important proteases found in the gastrointestinal (GI) tract (paper V).

Taken together, the work presented in this thesis illustrates the potential of using chemical synthesis approaches in protein engineering.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. viii, 79 p.
TRITA-BIO-Report, ISSN 1654-2312 ; 2014:3
Affibody molecules, albumin binding domain, ligation, protein synthesis, solid phase peptide synthesis
National Category
Biochemistry and Molecular Biology
Research subject
urn:nbn:se:kth:diva-141014 (URN)978-91-7595-004-4 (ISBN)
Public defence
2014-03-07, FR4 (Oskar Klein), AlbaNova Universitetscentrum, Stockholm, 10:00 (English)

QC 20140207

Available from: 2014-02-07 Created: 2014-02-05 Last updated: 2014-02-07Bibliographically approved

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Lindgren, JoelKarlström, Amelie Eriksson
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