Sulfo-NHS-LC-Biotin

Sulfo-NHS-LC-biotin (Sulfosuccinimidyl 6-(biotinamido) Hexanoate) is an amine-reactive biotinylation agent. As a water-soluble analog of NHS-LC-biotin, Sulfo-NHS-LC-biotin contains a negatively charged sulfonate group on the NHS ring structure, which creates sufficient polarity within the molecule and allows it to be directly added into aqueous reactions without prior dissolution of organic solvents. Sulfo-NHS-LC-biotin covalently binds to amine groups in proteins and other molecules through its NHS ester forming an amide linkage and releasing N-Hydroxysuccinimide. Sulfo-NHS-LC-biotin has a greater length (22.4 A) between a covalently modified molecule and the bicyclic biotin rings than NHS-biotin (13.5 A), which provides the probes a greater opportunity to reach the binding sites deeply buried inside the surface plane of proteins.

Reference

Bioconjugate Techniques , 2nd ed. By Greg T.Hermanson  (Pierce Biotechnology, Thermo Fisher Scientific, Rockford, IL).  Academic Press  (an imprint of Elsevier):  London, Amsterdam, Burlington, San Diego . 2008. ISBN 978-0-12-370501-3.

Targeted delivery of human VEGF gene via complexes of magnetic nanoparticle-adenoviral vectors enhanced cardiac regeneration.[Pubmed:22844395]

PLoS One. 2012;7(7):e39490.

This study assessed the concept of whether delivery of magnetic nanobeads (MNBs)/adenoviral vectors (Ad)-encoded hVEGF gene (Ad(hVEGF)) could regenerate ischaemically damaged hearts in a rat acute myocardial infarction model under the control of an external magnetic field. Adenoviral vectors were conjugated to MNBs with the Sulfo-NHS-LC-Biotin linker. In vitro transduction efficacy of MNBs/Ad-encoded luciferase gene (Ad(luc)) was compared with Ad(luc) alone in human umbilical vein endothelial cells (HUVECs) under magnetic field stimulation. In vivo, in a rat acute myocardial infarction (AMI) model, MNBs/Ad(hVEGF) complexes were injected intravenously and an epicardial magnet was employed to attract the circulating MNBs/Ad(hVEGF) complexes. In vitro, compared with Ad(luc) alone, MNBs/Ad(luc) complexes had a 50-fold higher transduction efficiency under the magnetic field. In vivo, epicardial magnet effectively attracted MNBs/Ad(hVEGF) complexes and resulted in strong therapeutic gene expression in the ischemic zone of the infarcted heart. When compared to other MI-treated groups, the MI-M(+)/Ad(hVEGF) group significantly improved left ventricular function (p<0.05) assessed by pressure-volume loops after 4 weeks. Also the MI-M(+)/Ad(hVEGF) group exhibited higher capillary and arteriole density and lower collagen deposition than other MI-treated groups (p<0.05). Magnetic targeting enhances transduction efficiency and improves heart function. This novel method to improve gene therapy outcomes in AMI treatment offers the potential into clinical applications.

Whole surface image of Mycoplasma mobile, suggested by protein identification and immunofluorescence microscopy.[Pubmed:22923591]

J Bacteriol. 2012 Nov;194(21):5848-55.

Mycoplasma mobile, a freshwater fish pathogen featured with robust gliding motility, binds to the surface of the gill, where it then colonizes. Here, to obtain a whole image of its cell surface, we identified the proteins exposed on the surface using the following methods. (i) The cell surface was labeled with sulfosuccinimidyl-6-(biotinamido) hexanoate and recovered by an avidin column. (ii) The cells were subjected to phase partitioning using Triton X-114, and the hydrophobic proteins were recovered. (iii) The membrane fraction was analyzed by two-dimensional gel electrophoresis. These recovered proteins were subjected to peptide mass fingerprinting, and a final list of 36 expressed surface proteins was established. The ratio of identified proteins to whole surface proteins was estimated through two-dimensional gel electrophoresis of the membrane fraction. The localization of three newly found proteins, Mvsps C, E, and F, has been clarified by immunofluorescence microscopy. Integrating all information, a whole image of the cell surface showed that the proteins for gliding that were localized at the base of the protrusion of flask-shaped M. mobile account for more than 12% of all surface proteins and that Mvsps, surface variants that were localized at both parts other than the neck, account for 49% of all surface proteins.

A novel reactive ester derivative of biotin with reduced membrane permeability for in vivo biotinylation experiments.[Pubmed:20821733]

Proteomics. 2010 Oct;10(19):3544-8.

The in vivo perfusion of rodent models of disease with biotin derivatives and the subsequent comparative proteomic analysis of healthy and diseased tissues represent a promising methodology for the identification of vascular accessible biomarkers. A novel, triply charged biotinylation reagent, NHS-beta-Ala-(L-Asp)(3)-biotin, was synthesized and validated in terms of its applicability for in vivo protein biotinylation. Compared to Sulfo-NHS-LC-Biotin, NHS-beta-Ala-(L-Asp)(3)-biotin exhibited a reduced membrane permeability and a preferential labeling of proteins localized in compartments readily accessible in vivo from the vasculature.

Characterization of tight junctions and their disruption by UVB in human epidermis and cultured keratinocytes.[Pubmed:21160495]

J Invest Dermatol. 2011 Mar;131(3):744-52.

It has not been confirmed whether tight junctions (TJs) function as a paracellular permeability barrier in adult human skin. To clarify this issue, we performed a TJ permeability assay using human skin obtained from abdominal plastic surgery. Occludin, a marker protein of TJs, was expressed in the granular layer, in which a subcutaneously injected paracellular tracer, Sulfo-NHS-LC-Biotin (556.59 Da), was halted. Incubation with ochratoxin A decreased the expression of claudin-4, an integral membrane protein of TJs, and the diffusion of paracellular tracer was no longer prevented at the TJs. These results demonstrate that human epidermis possesses TJs that function as an intercellular permeability barrier at least against small molecules ( approximately 550 Da). UVB irradiation of human skin xenografts and human skin equivalents (HSEs) resulted in functional deterioration of TJs. Immunocytochemical staining of cultured keratinocytes showed that occludin was localized into dot-like shapes and formed a discontinuous network when exposed to UVB irradiation. Furthermore, UVB irradiation downregulated the active forms of Rac1 and atypical protein kinase C, suggesting that their inactivation caused functional deterioration of TJs. In conclusion, TJs function as a paracellular barrier against small molecules ( approximately 550 Da) in human epidermis and are functionally deteriorated by UVB irradiation.

Delineating the extracellular water-accessible surface of the proton-coupled folate transporter.[Pubmed:24205192]

PLoS One. 2013 Oct 18;8(10):e78301.

The proton-coupled folate transporter (PCFT) was recently identified as the major uptake route for dietary folates in humans. The three-dimensional structure of PCFT and its detailed interplay with function remain to be determined. We screened the water-accessible extracellular surface of HsPCFT using the substituted-cysteine accessibility method, to investigate the boundaries between the water-accessible surface and inaccessible buried protein segments. Single-cysteines, engineered individually at 40 positions in a functional cysteine-less HsPCFT background construct, were probed for plasma-membrane expression in Xenopus oocytes with a bilayer-impermeant primary-amine-reactive biotinylating agent (sulfosuccinimidyl 6-(biotinamido) hexanoate), and additionally for water-accessibility of the respective engineered cysteine with the sulfhydryl-selective biotinylating agent 2-((biotinoyl)amino)ethyl methanethiosulfonate. The ratio between Cys-selective over amine-selective labeling was further used to evaluate three-dimensional models of HsPCFT generated by homology / threading modeling. The closest homologues of HsPCFT with a known experimentally-determined three-dimensional structure are all members of one of the largest membrane protein super-families, the major facilitator superfamily (MFS). The low sequence identity--14% or less--between HsPCFT and these templates necessitates experiment-based evaluation and model refinement of homology/threading models. With the present set of single-cysteine accessibilities, the models based on GlpT and PepTSt are most promising for further refinement.