Circular dichroism crystal

Hossein MB, Eng-Wiimot DL, Loghry RA, van der Helm D (1980) Circular Dichroism, Crystal Sructure, and Absolute Configuration of the Siderophore Ferric V/7 /7"-Triacetyl-fusarinine, EeC39H57NgOi5. J Am Chem Soc 102 5766... 

The Ca -ATPase has been crystallized in both conformations [119,152-155]. The two crystal forms are quite different [10,88-93,156-161], suggesting significant differences between the interactions of Ca -ATPase in the Ei and E2 conformations. Since the Ei-E2-transition does not involve changes in the circular dichroism spectrum of the Ca -ATPase [162], the structural differences between the two states presumably arise by hinge-like or sliding motions of domains rather than by a rearrangement of the secondary structure of the protein. 

The next 1 liter of eluent yielded no alkaloids, but the following 1 liter yielded the second alkaloid (1.78 g), which was crystallized from alcohol-hexane to yield 0.855 g of needles, mp 119-120°. This was identified as (+)-glauclne by direct comparison (melting point, mixture melting point, TLC, IR, and circular dichroism) with an authentic reference sample of (+)-glaucine. (+)-Glaucine was reported previously to be the major alkaloidal constituent of the heartwood (8). 

Probing Metalloproteins Electronic absorption spectroscopy of copper proteins, 226, 1 electronic absorption spectroscopy of nonheme iron proteins, 226, 33 cobalt as probe and label of proteins, 226, 52 biochemical and spectroscopic probes of mercury(ii) coordination environments in proteins, 226, 71 low-temperature optical spectroscopy metalloprotein structure and dynamics, 226, 97 nanosecond transient absorption spectroscopy, 226, 119 nanosecond time-resolved absorption and polarization dichroism spectroscopies, 226, 147 real-time spectroscopic techniques for probing conformational dynamics of heme proteins, 226, 177 variable-temperature magnetic circular dichroism, 226, 199 linear dichroism, 226, 232 infrared spectroscopy, 226, 259 Fourier transform infrared spectroscopy, 226, 289 infrared circular dichroism, 226, 306 Raman and resonance Raman spectroscopy, 226, 319 protein structure from ultraviolet resonance Raman spectroscopy, 226, 374 single-crystal micro-Raman spectroscopy, 226, 397 nanosecond time-resolved resonance Raman spectroscopy, 226, 409 techniques for obtaining resonance Raman spectra of metalloproteins, 226, 431 Raman optical activity, 226, 470 surface-enhanced resonance Raman scattering, 226, 482 luminescence... 

Over the past decade two forms of vibrational optical activity have become established. One is called vibrational circular dichroism (VCD), the extension of electronic circular dichroism into the infrared vibrational region of the spec-tram. The first measurements of VCD were reported by George Holzwarth and co-workers at the University of Chicago in 1973 for crystals (3) and 1974 for neat liquids (4). In VCD one measures the small difference in the absorption of a sample for left versus right circularly polarized incident infrared radiation. The early stages of the development of VCD have been reviewed from several perspectives (5-8). 

Of course, as with any spectroscopic technique, FTIR should not be used in isolation but always in conjunction with other techniques. FTIR is most usefully paired with circular dichroism in both the UV (i.e., ECD) and, if possible, also in the IR (i.e., VCD))64 70 73 110-112 Coupling IR to NMR studies can usefully aid interpretation of spectra from fluctional structures and can lead to some site-specific insight)113-1151 Even the generality of X-ray diffraction results (especially for linear oligopeptides whose conformation can be strongly influenced by intermolecular interactions in the crystal) can be tested by comparison of solid-state and solution-phase IR data with solution-phase CD data.1"6 "71... 

Recent investigations 1 2) of the hallucinogenic Mexican mint Salvia divinorum have resulted in the isolation of the phannacologically active diterpene salvinorin (divinorin) A (1) and its desacetyl analog salvinorin B (2). Extensive H and l C NMR studies on these /raz/.s-clerodanes and their derivatives, ) as well as single-crystal X-ray analysis, have led to the fonnulation of the structures of these compounds. The absolute chemistry of the salvinorins was postulated based on the observed negative n jc Cotton effect of the 1-ketone around 295 nm in their circular dichroism (CD) spectra. 1 2)... 

Vacuum-ultraviolet, circular dichroism (v.u.c.d.) measurements have been made on films and solutions of linear D-glucan in a study of the conformation of dextran and its oligomers.123 Film formation of the linear dextran was accompanied by crystallization, and the v.u.c.d. band was observed at 165 nm, in contrast to nonlinear dextran films displaying a band at 177 nm. The difference was ascribed to hydrogen bonding of the ring-oxygen atom in the crystalline state. 

The crystal structure and absolute configuration of l-( - )-[Cr(acac)3] has been reported.772 The circular dichroism of D-[Cr(acac)3] has been studied in the solid state and in solution.773 The rotational strengths of the d-d transitions are extensively discussed competing rather than reinforcing effects lead to the smaller rotational strengths observed for tris(acetylacetonates) as compared to tris-(ethylenediamine) or -oxalate complexes. 

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