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Biotechnol Bioeng. 2015 Jul;112(7):1327-34. doi: 10.1002/bit.25558. Epub 2015 Apr 30.

Site-specific fab fragment biotinylation at the conserved nucleotide binding site for enhanced Ebola detection.

Author information

1
Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana.
2
Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana. bbilgicer@nd.edu.
3
Advanced Diagnostics and Therapeutics, University of Notre Dame, Notre Dame, Indiana. bbilgicer@nd.edu.
4
Department of Chemistry and Biochemistry, University of Notre Dame, 182 Fitzpatrick Hall, Notre Dame, 46556, Indiana. bbilgicer@nd.edu.

Abstract

The nucleotide binding site (NBS) is a highly conserved region between the variable light and heavy chains at the Fab domains of all antibodies, and a small molecule that we identified, indole-3-butyric acid (IBA), binds specifically to this site. Fab fragment, with its small size and simple production methods compared to intact antibody, is good candidate for use in miniaturized diagnostic devices and targeted therapeutic applications. However, commonly used modification techniques are not well suited for Fab fragments as they are often more delicate than intact antibodies. Fab fragments are of particular interest for sensor surface functionalization but immobilization results in damage to the antigen binding site and greatly reduced activity due to their truncated size that allows only a small area that can bind to surfaces without impeding antigen binding. In this study, we describe an NBS-UV photocrosslinking functionalization method (UV-NBS(Biotin) in which a Fab fragment is site-specifically biotinylated with an IBA-EG11-Biotin linker via UV energy exposure (1 J/cm(2)) without affecting its antigen binding activity. This study demonstrates successful immobilization of biotinylated Ebola detecting Fab fragment (KZ52 Fab fragment) via the UV-NBS(Biotin) method yielding 1031-fold and 2-fold better antigen detection sensitivity compared to commonly used immobilization methods: direct physical adsorption and NHS-Biotin functionalization, respectively. Utilization of the UV-NBS(Biotin) method for site-specific conjugation to Fab fragment represents a proof of concept use of Fab fragment for various diagnostic and therapeutic applications with numerous fluorescent probes, affinity molecules and peptides.

KEYWORDS:

KZ52; UV-NBS method; biotinylation; ebola; fab; nucleotide binding site (NBS)

PMID:
25678249
DOI:
10.1002/bit.25558
[Indexed for MEDLINE]

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