Atomic force microscopy (AFM) has turned out to be the most relevant for (membrane) proteins. Because it can be applied in aqueous solution, it has opened the way to follow in time the formation of protein arrays lipid bilayers (Reviakine et al. 1998). Although high quality AFM images
are not easy to make in large numbers, they have a much lower noise level than EM images. Combined with a good resolution, this has enabled researchers to visualize, for instance, the small units in the rings of prokaryotic antenna complexes. This is one of the lasting contributions of this technique to the field of photosynthesis. Scheuring and Sturgis (2009) give an overview of AFM applied to the bacterial photosynthetic apparatus. Last but not least, we have a contribution on nuclear magnetic find more resonance Selleck FG4592 (NMR). NMR can be used in several ways, such as the characterization of small molecules from their spectra in organic chemistry. In the field of biophysics, its largest impact is on protein structure determination in solution. By the pioneering work of Kurt Wüthrich NMR became a useful technique in the 1980s to solve the structure of
small protein molecules. One of the examples in photosynthesis is subunit PsaC from photosystem I (Antonkine et al. 2002). NMR can also be applied as an imaging tool, and magnetic resonance imaging (MRI) became a useful method in the same time. In its early years, the technique Selleckchem Vorinostat was referred to as nuclear magnetic resonance imaging. However, as the word nuclear was associated in the public mind with ionizing radiation exposure, the shorter abbreviation MRI became more popular. It provides on the scale of a human body a much greater contrast between the different soft tissues of the body than PRKACG computed tomography with X-rays. Although MRI delivers a spatial resolution as good as a strong
magnifying glass, it certainly delivers an abundant amount of information in addition to a reasonable spatial and temporal resolution. Part of this information, such as the flow of water in plant tissue, is very difficult to measure or cannot be measured using other techniques. This is the scope of the MRI paper of Van As et al. in the last contribution on imaging methods (Van As et al. 2009). Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. References Amesz J, Hoff AJ (eds) (1996) Biophysical techniques in photosynthesis. Kluwer Academic Publishers, Dordrecht Antonkine ML, Liu G, Bentrop D, Bryant DA, Bertini I, Luchinat C, Golbeck JH, Stehlik D (2002) Solution structure of the unbound, oxidized Photosystem I subunit PsaC, containing [4Fe-4S] clusters F(A) and F(B): a conformational change occurs upon binding to photosystem I.
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