Neutrons for biologists: a beginner's guide, or why you should consider using neutrons

Abstract

From the structures of isolated protein complexes to the molecular dynamics of whole cells, neutron methods can achieve a resolution in complex systems that is inaccessible to other techniques. Biology is fortunate in that it is rich in water and hydrogen, and this allows us to exploit the differential sensitivity of neutrons to this element and its major isotope, deuterium. Furthermore, neutrons exhibit wave properties that allow us to use them in similar ways to light, X-rays and electrons. This review aims to explain the basics of biological neutron science to encourage its greater use in solving difficult problems in the life sciences.

Antibody adsorption on the surface of water studied by neutron reflection

“…In this study, we apply neutron reflection to the problem of understanding mAb adsorption to an interface (reviewed in ref. 17). Neutron reflection has enabled molecular models of protein adsorption to be constructed, 18 has been used to determine the orientation of antibodies non-specifically adsorbed at the solid/liquid interface, 19 and has yielded the structural characterization of membrane proteins in bilayer models resting on a water-filled layer.…”

Adsorption behavior of a human monoclonal antibody at hydrophilic and hydrophobic surfaces

“…In this manner TIRF is a relatively straightforward bench-top technique allowing determination of adsorption/ desorption kinetics for a fluorescently labeled protein at the solid/liquid interface; however, transport limited kinetics are only maintained for low protein concentrations and TIRF does not provide molecular-level information of the nature of the adsorbed protein layer, such as orientation of the protein molecules at the surface, and the build-up of multiple protein layers. To ascertain this information for protein adsorbed from relatively high concentration solutions, we characterized the adsorbed protein layers using neutron reflectometry (NR, a general technique described elsewhere 26 ) NR has been used to define the orientation of antibodies non-specifically adsorbed at the solid/liquid interface 19 and antibodies non-covalently bound at surfaces engineered to harbor specific capture ligands. 27 By analyzing data generated by TIRF and NR experiments, we describe the differential adsorption/desorption of a human monoclonal antibody at silica and alkyl-silanized silica surfaces from aqueous solution of varying pH in the presence and absence of polysorbate 20/80 above and below their CMC.…”

Structural Biology: A Century-long Journey into an Unseen World

“…Although SAXS provides more precise measurements, SANS has a particular advantage in the analysis of complexes, since selective deuteration of components within a complex and contrast matching by adjusting the H 2 O/ D 2 O mix in the surrounding solvent allows their position and shape within the complex to be identified (Lakey 2009). Though less commonly applied, the contrast-matching trick can also be performed in SAXS using sucrose or INTERDISCIPLINARY SCIENCE REVIEWS, Vol.…”

“…Neutron and X-ray crystallography are complementary since neutrons interact with the nucleus at the heart of an atom while X-rays scatter primarily from the electron clouds that surround them (Lakey 2009). This complementarity is sharpened because neutrons interact most strongly with hydrogen atoms, which, with just a single electron, are difficult to detect by X-ray methods.…”