Nuclear magnetic resonance properties, commonly-studied

To develop a unifying view of iron center catalysis, properties of the iron center in individual enzymes must be determined. Obviously, the definitive solution for the structure is atomic resolution of the active enzyme and postulated intermediates determined by diffraction or nuclear magnetic resonance (NMR) spectroscopy. Just as obviously, these methods are limited by enormous time, effort, and instrumentation requirements as well as by practical and theoretical considerations. This point is emphasized by the paucity of available protein structures. In addition to the strictly structural details of the iron center, chemical and physical properties are required and, in some cases, these results augment diffraction or NMR structural studies. Discussed below are a few of the more common processes by which this information is obtained. 

The characterisation of a stimulus responsive surface in general includes two aspects verification of the surface composition and evaluation of the materials response due to the presence of the stimulus. Although a variety of techifiques are available to characterise peptides and their stimulus-responsive properties in solution and in bulk, many of these are not compatible with surface-immobilised peptides. Hence, a common approach is to characterise the peptide material in solntion before attachment to the surface. UV-based turbidity measurements (Lee et al., 2(X)9 Nath Chilkoti, 2003 Teeuwen et al., 2009) and calorimetry (Barbosa et al., 2009) are used to determine the LCST of ELPs. The isomerisation of azobenzene can be studied with UV absorption, nuclear magnetic resonance spectroscopy, and high-performance Uqnid chromatography (Anemheimer et al., 2005 Hayashi et al., 2007), and CD is nsed to determine the presence of helices in a peptide (Minelli et al., 2013 Yasntomi et al., 2005). Non-solution-based methods that can be used to characterise responsive peptide surfaces will be discussed in more detail below. 

The most common characterization techn iques used in refineries to monitor the changes in catalyst activity during commercial operation are textural properties (surface area, pore volume, average pore diameter, and pore size distribution) determined by nitrogen adsorption/desorption metals content (mainly Ni and V) by atomic absorption and carbon content by combustion. There are more advanced characterizations techniques that are mostly employed by researchers for more detailed studies of catalyst deactivation such as Nuclear Magnetic Resonance (NMR), x-ray Photoelectron Spectroscopy... 

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