Single molecule fluorescence measurements provide valuable information about biomolecular mechanisms but there are a number of parameters that have to be checked when planning a single molecule experiment in order to access whether the biological process can be studied with single molecule techniques. These considerations mainly concern the concentration range, the time scale of the molecular process and the availability of efficiently labelled Caspase inhibitor molecules of the system under investigation. Recent developments brought about optimised fluorescent

labelling protocols that allow selective labelling of unique reactive moieties of UAAs even in cell extracts. A combination with the powerful SiMPull technique, where minimal amounts of labelled species are sufficient for a single molecule experiment, potentially allow for single cell investigations checking on, for example, protein levels in differently stimulated cells. Finally the progressive fluorescence enhancement

approaches that allow the detection of individual molecules at much higher and much lower concentrations than has been possible so far extend the range of applications to diagnostics and transient biological interactions in a high-throughput format. Papers of particular Thiazovivin clinical trial interest, published within the period of review, have been highlighted as: • of special interest This work was supported by a DFG grant (GR 3840/2-1) and by the German Israel Foundation (Young Scientist Program 2292-2264.13/2011) Florfenicol to D.G. Funding from Deutsche Forschungsgemeinschaft (DFG)Ti329/6-1, and a Starting Grant of the European Research (SiMBA) to P.T. is gratefully acknowledged. F.W. is supported by a Wellcome Trust Investigator AwardWT096553MA, and BBSRC grant BB/H019332/1. We are grateful to A. Gietl, A. Gust and A. Zander for technical help. ”
“Current Opinion in Chemical Biology 2013, 17:59–65 This review comes from a themed issue on Omics Edited by Matthew Bogyo and Pauline M Rudd For a complete

overview see the Issue and the Editorial Available online 19th January 2013 1367-5931/$ – see front matter, © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.cbpa.2012.12.024 The discovery of ubiquitin was made within the context of experiments on ATP-dependent protein breakdown and turn-over [1]. Ubiquitin is a small 76 amino acid protein that is highly conserved across plants, yeast and mammals. Nearly ∼1000 enzymes are involved in the recognition of ubiquitin and its attachment to and cleavage from other protein substrates, suggesting that this posttranslational modification must play a fundamental role in biology far beyond protein degradation. Ubiquitin is found to be covalently attached to other proteins either as poly-ubiquitin chains or mono-ubiquitin, and the chains consist of linkages through all seven ubiquitin encoded lysines (lys6, 11, 27, 29, 33, 48 and 63) as well as the N-terminus [2•].