Anatrace is excited to offer 10% savings on our Non-Ionic Amphipol (NAPol) - the newest addition to our amphipol family.

As we ring in the first quarter of 2021, we continue to highlight our newest edition to the Anatrace amphipol family, the Non-Ionic Amphipol (NAPol). A comprehensive background on NAPols can be found in our January 2021 Newsletter and the below abstract highlights key developments of the NAPol since their initial introduction in our August 2019 Newsletter. As a result of these developments and further highlights, we'd like to offer additional savings on all NAPol orders now through the end of April 2021, use coupon code NAPol at checkout to get 10% off your next order. Order Now!

Key NAPol Developments

Amphipols (APols) are amphipathic polymers that were designed and validated as mild alternatives to classical detergents. Accordingly, most integral membrane proteins (MPs) are much more stable in APols than they are in detergent solutions.

The first designed polyacrylate-based A8-35 [1] has been so far the most widely used APol [2,3]. However, acidic pH or the presence of multivalent cations can result in A8-35 aggregation. These constraints prompted the development of chemically different APols, including zwitterionic APols, sulfonated APols (SAPols), and NAPols [reviewed in 4]. NAPols are the most stabilizing derivatives [5] and therefore represent a new, milder tool for the manipulation of MPs.

The most advanced series of NAPols relies on homotelomerization of a monomer carrying two glucose moieties and a single alkyl chain [6, 7]. These new polymers which are the first homopolymeric APols to be validated, are easier to synthesize in a batch-to-batch reproducible manner. These are less heterogeneous at the molecular level, because of the absence of the group distribution variability that is typically inherent to copolymerization or random grafting [1, 7].

NAPols were found able to keep MPs water-soluble in the absence of detergent [7]. Analytical ultracentrifugation (AUC), small angle neutron scattering (SANS) and size exclusion chromatography (SEC) studies showed that, homopolymeric NAPols spontaneously organize into small, micelle-like particles [7], similar in size to those formed by A8-35. They were shown to efficiently trap two model MPs, bacteriorhodopsin (BR) from Halobium salinarum and the outer membrane protein X (OmpX) from Escherichia coli. MP/NAPol complexes are well-defined and their size is comparable to that of MP/A8 35 ones [7].

This most advanced series of NAPols, was successfully used for several membrane protein applications: (a) stabilization of membrane proteins [5] including super complexes [8, 9] and GPCRs [10]; (b) cell-free expression [5]; (c) mass spectrometry [11]; NMR spectrometry [12, 13]; cryoEM [14, 15] as well as biomedical applications such as delivery of MPs to pre-existing membranes [16] and MP immobilization onto solid supports [17].
 

References:

[1] C. Tribet, et al, Amphipols: polymers that keep membrane proteins soluble in aqueous solutions, P. Natl. Acad. Sci. U. S. A. 93 (1996) 15047-15050.

[2] J. -L. Popot, Amphipols, nanodiscs, and fluorinated surfactants: three nonconventional approaches to studying membrane proteins in aqueous solutions, Ann. Rev. Biochem. 79 (2010) 737-775.

[3] J.-L. Popot, et al, Amphipols From A to Z. Ann. Rev. Biophys. 40 (2011) 379-408.

[4] M. Zoonens, J. -L. Popot, Amphipols for each season, J. Membr. Biol. 247 (2014) 759-96.

[5] P. Bazzacco, et al, Nonionic homopolymeric amphipols: application to membrane protein folding, cell-free synthesis, and solution nuclear magnetic resonance, Biochemistry. 51 (2012) 1416-1430.

[6] K. S. Sharma, et al and Determination of Polymerization Rate Constants of Glucose-Based Monomers, Des. Monomers Polym. 14 (2011) 499-513.

[7] K. S. Sharma, et al, Non-Ionic Amphiphilic Homopolymers: Synthesis, Solution Properties, and Biochemical Validation, Langmuir. 28 (2012) 4625-4639.

[8] Nicoletta Liguori, et al, Regulation of Light Harvesting in the Green Alga Chlamydomonas reinhardtii: The C-Terminus of LHCSR Is the Knob of a Dimmer Switch, Journal of American Chemical Society. 135 (2013) 18339-18342.

[9] Milena Opačić, et al. Amphipols and photosynthetic light-harvesting pigment-protein complexes. Journal of Membrane Biology. 247 (2014) 1031-1041. 

[10] Rita Rahmeh, et al. Structural insights into biased GPCR signaling revealed by fluorescence spectroscopy. Proceedings of the National Academy of Sciences USA. 109 (2012) 6733-6738.

[11] Cherine Bechara, et al. Maldi-TOF mass spectrometry analysis of amphipol-trapped membrane proteins. Analytical Chemistry. 84 (2012) 6128-6135. 

[12] Noelya Planchard, et al. The use of amphipols for solution NMR studies of membrane proteins: advantages and constraints as compared to other solubilizing media. Journal of Membrane Biology. 247 (2014) 827-842.

[13] Zsofia Solyom, et al. The Disordered Region of the HCV Protein NS5A: Conformational Dynamics, SH3 Binding, and Phosphorylation. Biophysical Journal. 109 (2015) 1483-1496.

[14] Thomas Bausewein et al. Cryo-EM Structure of the TOM Core Complex from Neurospora crassa. Cell. 170 (2017) 693-700.

[15] Hisako Kubota-Kawai, et al Ten antenna proteins are associated with the core in the supramolecular organization of the photosystem I supercomplex in Chlamydomonas reinhardtii. Journal of Biological Chemistry. 294 (2019) 4304-4314. 

[16] Alexander Kyrychenko, et al. Folding of diphtheria toxin T-domain in the presence of amphipols and fluorinated surfactants: Toward thermodynamic measurements of membrane protein folding. Biochimica et Biophysica Acta. 1818 (2012) 1006-1012.

[17] Michaël Bosco, et al. Biotinylated non-ionic amphipols for GPCR Ligands Screening. Methods. 180 (2020) 69-78.