Probes of Structure

The X-ray crystal structures of a variety of high- and low-oxidation-state nickel complexes are now known. These are introduced throughout the text in Section IV,A and the important points are summarized in 

Tetragonally compressed Octahedral Tetragonally elongated Square planar  

There is no generalized treatment of the UV/visible spectra of these complexes since they tend to be dominated by low-energy charge transfer bands which obscure details of the d-d structure. In a few instances, circular dichroism data have been reported, but detailed interpretation has not been attempted (19). 

Coordination Environments and Structural Chemistry 1. Amines, Imines, and Oximes 

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Madey T E 1986 Electron- and photon-stimulated desorption probes of structure and bonding at surfaces Science 234 316... 

Friedman J M 1994 Time-resolved resonance Raman spectroscopy as probe of structure, dynamics, and reactivity in hemoglobin Methods Enzymol. 232 205-31... 

Figure 15. Complex plane impedance plots for polypyrrole at (A) 0.1, (B) -0.1, (C) -0.2, (D) -0.3, and (E) -0.4 V vs. Ag/AgCl in NaCl04(aq). The circled points are for a bare Pt electrode. Frequencies of selected points are marked in hertz. (Reprinted from X. Ren and P. O. Pickup, Impedance measurements of ionic conductivity as a probe of structure in electrochemi-cally deposited polypyrrole films, / Electmanal Chem. 396, 359-364, 1995, with kind permission from Elsevier Sciences S.A.)...

Ballesteros, J. A. and Weinstein, H. (1995) Integrated methods for the construction of three-dimensional models and computational probing of structure-function relations in G protein-coupled receptors. Methods Neurosci. 25, 366 128. 

Nickel (continued) polysulfide complex, 31 98 half chair conformation, 31 115 porphyrin complexes, 32 13 in proteins, 47 284-285 quadruply bridged dimers, 40 211-214 steric structures, 40 190-194 quaternary phosphonium salts of, 6 31-32 redox chemistry probes of structure, 32 243-245 steric and electronic requirements, 32 242-243... 

Horrocks, W. de W. Jr. Sudnick, D. R. Lanthanide ion probes of structure in biology. Laser-induced luminescence decay constants provide a direct measure of the number of metal-coordinated water molecules. J. Am. Chem. Soc. 1979,101(2), 334-340. 

Chemical Modification as a Probe of Structure and Function Louis A. Cohen... 

Hays, Melanie L., and Hanusa, Timothy, P., Substituent Effects as Probes of Structure and... 

It is clear that Mn and Gd can be sensitive EPR probes of structure and function in membrane enzyme systems. If problems of purity and concentration can be overcome, several other membrane enzymes should be amenable to EPR investigations of the type described here. Moreover, the combination of nuclear relaxation studies and EPR studies of free and bound metals can provide sufficient data for the construction of models of active sites for membrane enzymes. For each paramagnetic probe which can be located unambiguously and uniquely at the active site, one more spatial dimension is added to the picture. Thus the identification of a single Mn2+ site on the (Na+ + K+)-ATPase has permitted the determination of three distances between Mn2+ and... 

Luminescence has proven a useful probe of structure and dynamics in a broad range of heterogeneous media, from zeolites to micelles to biomaterials. The sensitivity of this process to its environment, and its ease of detection, make it a highly versatile analytical tool. To date, luminescence as a probe of solid-liquid interfacial processes in SAMs is still relatively limited. However, with the development of fluorescence-based analytical methods of increasing spatial and temporal resolution, it is likely to be used increasingly in answering fundamental questions regarding monolayer behavior. 

The 33S chemical shift trend has been compared to the behaviour of more common nuclei, such as 13C, 170 and 15N, and in many cases it has been demonstrated that the 33S chemical shift is a better probe of structural properties. Many correlations among the chemical shifts of these nuclei in similar electronic environments have been found (e.g. between the 33S chemical shifts in sulphonates and the 13C chemical shift carboxylic acids38 or between the 33S chemical shift in sulphones and O in ethers or C in alkanes ). This suggests that 33S is affected by the same kind of electronic and steric influences as 13C, 15N and 170. 

How general are such conclusions Do they apply to more complex proteins Are there more elusive features that influence turn preferences Selection for catalytic activity, an extremely sensitive probe of structural integrity, has the potential to reveal more subtle sequence preferences than simple screening protocols. We tested this premise using the EcCM enzyme (Fig. 3.4B) as a template [85]. The two identical polypeptides that make up this helical bundle protein consist of three helices joined by two loop segments (Fig. 3.12A) [33], The L2 loop connecting the H2 and H3 helices lies farthest from the active site and was targeted for analysis. 

Hays, Melanie L.. and Hanusa, Timothy, P., Substituent Effects as Probes of Structure and Bonding in Mononuclear Metallocenes. Hemme, Ina, see Klingebiel, Uwe Hopkins, Michael D., see Manna, Joseph John, Kevin D., see Manna. Joseph Kawachi, Atsushi, see Tamao. Kohei... 

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