ABSTRACT
Site-Directed Spin Labelling (SDSL) technique is based on the attachment of a paramagnetic label onto a specific position of a protein (or other bio-molecules) and the subsequent study by Electron Paramagnetic Resonance (EPR) spectroscopy. In particular, continuous-wave EPR (cw-EPR) spectra can detect the local conformational dynamics for proteins under various conditions. Moreover, pulse-EPR experiments on doubly spin-labelled proteins allow measuring distances between spin centres in the 1.5-8 nm range, providing information about structures and functions. This review focuses on SDSL-EPR spectroscopy as a structural biology tool to investigate proteins using nitroxide labels. The versatility of this spectroscopic approach for protein structural characterization has been demonstrated through the choice of recent studies. The main aim is to provide a general overview of the technique, particularly for non-experts, to spread the applicability of this technique in various fields of structural biology.
Subject(s)
Nitrogen Oxides/chemistry , Proteins/chemistry , Spin Labels/chemical synthesis , Electron Spin Resonance Spectroscopy/methods , Molecular ConformationABSTRACT
A database management system has been realized that, by taking physical and chemical properties (the complex refractive index and the size distribution) of basic components as its starting point, allows the user to obtain optical properties of default as well as user-defined aerosol classes. Default classes are defined in accordance with the most widely known and used aerosol models. We obtain user-defined classes by varying the mixing ratio of components, creating new mixtures of default components, or by defining user components, thereby supplying the size distribution and the refractive index. The effect of relative humidity (RH) on the refractive index and the size distribution is properly accounted for up to RH = 99%. The two known mechanisms of obtaining classes from components are allowed (internal or external mixing).