2jb5

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==Overview==
==Overview==
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Tetrasulfocyanine (TSC) has been described as a fluorescent probe for tumour imaging. The complex of TSC and the Fab antibody fragment MOR03268 has been crystallized in three different crystal forms. MOR03268 was identified from the HuCAL GOLD library and further optimized to bind TSC with high affinity (Kd = 0.6 nM). For two of the three crystal forms (forms 1 and 2), data sets could be collected to 2.8 and 2.85 A resolution, respectively. Form 1 belongs to space group I222, with unit-cell parameters a = 72, b = 99, c = 154 A. Form 2 belongs to space group P4(3)2(1)2, with unit-cell parameters a = b = 77, c = 379 A. Form 3 only diffracted to 8 A and was not analyzed further. Molecular-replacement solutions for forms 1 and 2 were found and rebuilding and refinement is in progress. Form 1 contains one Fab molecule per asymmetric unit, while form 2 harbours two. Judging from the green colour of the crystals, both forms contain the Fab molecule bound to the green TSC dye and in both the hydrolysis-sensitive dye molecule is protected from degradation for several weeks to months. The structures should reveal the molecular basis of the high-affinity recognition of TSC by the Fab molecule MOR03268.
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Molecular interactions between near-IR fluorescent probes and specific antibodies may be exploited to generate novel smart probes for diagnostic imaging. Using a new phage display technology, we developed such antibody Fab fragments with subnanomolar binding affinity for tetrasulfocyanine, a near-IR in vivo imaging agent. Unexpectedly, some Fabs induced redshifts of the dye absorption peak of up to 44 nm. This is the largest shift reported for a biological system so far. Crystal structure determination and absorption spectroscopy in the crystal in combination with microcalorimetry and small-angle X-ray scattering in solution revealed that the redshift is triggered by formation of a Fab dimer, with tetrasulfocyanine being buried in a fully closed protein cavity within the dimer interface. The derived principle of shifting the absorption peak of a symmetric dye via packaging within a Fab dimer interface may be transferred to other diagnostic fluorophores, opening the way towards smart imaging probes that change their wavelength upon interaction with an antibody.
==About this Structure==
==About this Structure==
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==Reference==
==Reference==
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Crystallization and molecular-replacement solution of a diagnostic fluorescent dye in complex with a specific Fab fragment., Hillig RC, Baesler S, Urlinger S, Stark Y, Bauer S, Badock V, Huber M, Bahr I, Schirner M, Licha K, Acta Crystallogr Sect F Struct Biol Cryst Commun. 2007 Mar 1;63(Pt, 3):217-23. Epub 2007 Feb 23. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17329818 17329818]
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Fab MOR03268 triggers absorption shift of a diagnostic dye via packaging in a solvent-shielded fab dimer interface., Hillig RC, Urlinger S, Fanghanel J, Brocks B, Haenel C, Stark Y, Sulzle D, Svergun DI, Baesler S, Malawski G, Moosmayer D, Menrad A, Schirner M, Licha K, J Mol Biol. 2008 Mar 14;377(1):206-19. Epub 2008 Jan 5. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=18241888 18241888]
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
[[Category: Single protein]]
[[Category: Single protein]]
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[[Category: tsc]]
[[Category: tsc]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:01:25 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Mar 14 09:42:43 2008''

Revision as of 07:42, 14 March 2008

Image:2jb5.jpg

2jb5, resolution 2.8Å

Drag the structure with the mouse to rotate

FAB FRAGMENT IN COMPLEX WITH SMALL MOLECULE HAPTEN, CRYSTAL FORM-1

Overview

Molecular interactions between near-IR fluorescent probes and specific antibodies may be exploited to generate novel smart probes for diagnostic imaging. Using a new phage display technology, we developed such antibody Fab fragments with subnanomolar binding affinity for tetrasulfocyanine, a near-IR in vivo imaging agent. Unexpectedly, some Fabs induced redshifts of the dye absorption peak of up to 44 nm. This is the largest shift reported for a biological system so far. Crystal structure determination and absorption spectroscopy in the crystal in combination with microcalorimetry and small-angle X-ray scattering in solution revealed that the redshift is triggered by formation of a Fab dimer, with tetrasulfocyanine being buried in a fully closed protein cavity within the dimer interface. The derived principle of shifting the absorption peak of a symmetric dye via packaging within a Fab dimer interface may be transferred to other diagnostic fluorophores, opening the way towards smart imaging probes that change their wavelength upon interaction with an antibody.

About this Structure

2JB5 is a Single protein structure of sequence from Homo sapiens with as ligand. Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

Fab MOR03268 triggers absorption shift of a diagnostic dye via packaging in a solvent-shielded fab dimer interface., Hillig RC, Urlinger S, Fanghanel J, Brocks B, Haenel C, Stark Y, Sulzle D, Svergun DI, Baesler S, Malawski G, Moosmayer D, Menrad A, Schirner M, Licha K, J Mol Biol. 2008 Mar 14;377(1):206-19. Epub 2008 Jan 5. PMID:18241888

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