Circular dichroism spectroscopy spectra

The availability of the purified transporter in large quantity has enabled investigation of its secondary structure by biophysical techniques. Comparison of the circular dichroism (CD) spectrum of the transporter in lipid vesicles with the CD spectra of water-soluble proteins of known structure indicated the presence of approximately 82% a-helix, 10% ) -turns and 8% other random coil structure [97]. No / -sheet structure was detected either in this study or in a study of the protein by the same group using polarized Fourier transform infrared (FTIR) spectroscopy [98]. In our laboratory FTIR spectroscopy of the transporter has similarly revealed that... 

The absolute configuration of C-3 of the chromophore 459 of isopyoverdins was determined to be S from the circular dichroism (CD) spectrum (Cotton effect +242 nm, —290 nm, +358 nm) of 460 obtained from isopyoverdin by acidic hydrolysis <2001T1019>. Diorganotin(iv) complexes with 4//-pyrido[l,2-/z pyrimidin-4-ones 461 <1996AOM47>, complexes of 2-methyl- and 2-methyl-8-nitro-9-hydroxy-4//-pyrido[l,2-tf]pyrimidin-4-ones with Ag(i), Cu(ll), Ni(n), Co(n), and Mn(n) ions <2000RJD587>, 2,4-dimethyl-9-hydroxypyrido[l,2-tf]pyrimidinium perchlorate and its complexes with prasedynium, neodymium, samarium, and europium <2000RJD310> were characterized by UV spectroscopy. 

Fig. 5. Circular dichroism spectroscopy of peptide (120-189) fused to a 6xHis-tag. The circular dichroism spectrum of 6xHis-rCla h6 (120-189) (protein concentration was 27 piMin salt-free water) was recorded on a Jasco spectropolarimeter (J-810) at 185-260nm. Computer-assisted analysis of the data showed that the peptide is folded with 11% helix, 35% (3-sheet, 27% loop and 26% random structural elements.

As shown previously (19) by circular dichroism spectroscopy, the disulfide linked c-Myc-Max heterodimeric LZ is highly helical (>90%) between pH 4.0 and pH 7.0. We present in Fig. 2 the amide-amide region from a NOESY spectrum recorded at 25°C and pH 4.7. Extensive sequential dNN (t, j+1) NOE s typical for a-helices (24) can be seen. Despite poor chemical shift dispersion of the a-protons, a significant portion of the short range doN (i.i+3 and i, i+4) d p (/, i+3) a-helical connectivities (24) could be unambiguously identified. In summary, enough a-... 

For structural studies of PrP, recombinant proteins were expressed in Escherichia coli. The constructs used contain either the intact polypeptide chain of the mature form of natural PrP (Fig. 1), possibly with some additional, construct-related residues at either chain end, or fragments thereof. Presently it appears impractical to envisage three-dimensional structure determinations with mammalian prion proteins from natural sources. However, sufficient amounts of natural PrP have been isolated to enable qualitative comparative studies with the recombinant protein by optical spectroscopy. Overall, these experiments indicate close similarity between the natural and the corresponding recombinant prion protein. Thus, the circular dichroism (CD) spectrum of monomeric hamster PrP extracted from hamster brains into a micellar environment of 30 mM w-octyl-P-glucopyranoside at pH 7.5 is typical for... 

By application of valence shell electron energy loss spectroscopy, inner shell electron energy loss spectroscopy, magnetic circular dichroism spectroscopy, as well as photoelectron and electron transmission spectroscopy it can be deduced that the ji-electron system of borazine resembles that of benzene [8]. Table 4/13 presents the Rydberg term value matrix and Table 4/14 the energies and assignments from the electron energy loss spectrum (EELS) [8]. 

In a few instances the technique of magnetic circular dichroism (MCD) spectroscopy has been used to corroborate assignments based on UV-visible spectroscopy. For example, the assignment of the intense 360 nm band for [S,N,Y to a r (2e") r (2a2") (HOMO LUMO) excitation has been confirmed by the measurement of the MCD spectrum of The MCD spectrum of [S4N3] indicates that each of the... 

Circular dichroism (c.d.) spectroscopy measures the difference in absorption between left- and right-circularly polarized light by an asymmetric molecule. The spectrum results from the interaction between neighboring groups, and is thus extremely sensitive to the conformation of a molecule. Because the method may be applied to molecules in solution, it has become popular for monitoring the structure of biological molecules as a function of solvent conditions. 

Of the visible spectroscopic techniques, CD spectroscopy has seen the most rapid and dramatic growth. The far-UV circular dichroism spectrum of a protein is a direct reflection of its secondary structure [71]. An asymmetrical molecule, such as a protein macromolecule, exhibits circular dichroism because it absorbs circularly polarized light of one rotation differently from circularly polarized light of the other rotation. Therefore, the technique is useful in determining changes in secondary structure as a function of stability, thermal treatment, or freeze-thaw. 

To obtain statistically significant comparisons of ordered and disordered sequences, much larger datasets were needed. To this end, disordered regions of proteins or wholly disordered proteins were identified by literature searches to find examples with structural characterizations that employed one or more of the following methods (1) X-ray crystallography, where absence of coordinates indicates a region of disorder (2) nuclear magnetic resonance (NMR), where several different features of the NMR spectra have been used to identify disorder and (3) circular dichroism (CD) spectroscopy, where whole-protein disorder is identified by a random coil-type CD spectrum. 

The heme moiety provides de novo designed heme proteins with an intrinsic and spectroscopically rich probe. The interaction of the amide bonds of the peptide or protein with the heme macrocycle provides for an induced circular dichroism spectrum indicative of protein-cofactor interactions. The strong optical properties of the heme macrocycle also make it suitable for resonance Raman spectroscopy. Aside from the heme macrocycle, the encapsulated metal ion itself provides a spectroscopic probe into its electronic structure via EPR spectroscopy and electrochemistry. These spectroscopic and electrochemical tools provide a strong quantitative base for the detailed evaluation of the relative successes of de novo heme proteins. 

The vibrational circular dichroism(VCD) spectroscopy can be used to elucidate the stereochemistries of chiral molecules, including the accurate estimation of enantiomeric excess and their absolute configrations[20]. Optically pure samples as well as a racemic sample(c) were used as a reference to compare the VCD spectra. Three VCD spectra are shown in Fig. 7 a spectrum of 99 % ee R(-)-1-phenyl 1,2-ethanediol(a) and that of 99 % ee S(+ )-1-phenyl l,2-ethanediol(b) obtained from Aldrich Co., and the other is that of the product obtained on the Ti-MCM-41/chiral Co(HI) salen catalyst(d). 

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