Blues amino ligands

Fig. 2 Chemical shift perturbation and chemical shift mapping, (a) Portions of the [15N, 1H]-HSQC spectra of Bcf-xL recorded in absence (black) and in presence of each of the four molecules (in colors). Resonance assignments for amino acid residues that exhibit large shifts are reported, (b) Structure of Bc1-Xl in complex with the BH3 peptide from Bak (PDB code 1BXL) showing the chemical shift changes in Bcl-xL upon ligand binding (blue, large shits yellow, no shifts the Bak peptide is reported in cyan). Adapted from [48]...

Mavicyanin (Mj = 18,000) is obtained from green squash (Cucurbito pepo medullosa), where it occurs alongside ascorbate oxidase [64]. It has a peak at 600 nm (e 5000 M cm and reduction potential of 285 mV. Further studies on this and the mung bean and rice bran proteins [65, 66] would be of interest. All the above type 1 Cu proteins have an intense blue color and characteristic narrow hyperfine EPR spectrum for the Cu(II) state. Table 3 summarizes the properties of those most studied. There is some variation in reduction potential and position of the main visible absorbance peak. In the case of azurin, for example, the latter is shifted from 597 to 625 nm. Stellacyanin has no methionine and the identity of the fourth ligand is therefore different [75]. The possibility that this is the 0(amide) of Gln97 has been suggested [63b]. It now seems unlikely that the disulfide is involved in coordination. Stellacyanin has 107 amino acids, with carbohydrate attached at three points giving a 40% contribution to the M, of 20,000 [75]. 

Pinacolone, o-(diphenylphosphino)benzoyl-coordination chemistry, 401 Piperidine, IV-hydroxy-metal complexes, 797 pA a values azole ligands, 77 Plant roots amino acids, 962 carboxylic acids, 962 Plastocyanin copper binding site, 557 copper(II) complexes, 772 copper(II) site in, 770 Platinum, dichlorobis(benzonitrile)-IR spectrum, 264 Platinum, cis-dichlorodianunine-antitumor activity, 34, 979 Platinum, ethylenebis(triphenylphosphine)-reactions with 5,6-dimethyl-2,l,3-benzothiadiazole, 194 Platinum blue formation, 265 Platinum complexes acetylacetone reactions, 380 amides, 491 amidines... 

Amino-4-methylpyrimidine (10 mmol) was dissolved in 25 mL of water. C u(C104)2 6LLO (10 mmol) was also dissolved in 25 mL of water. The Cu(II) salt solution was then added slowly to the ligand solution, preventing any precipitation, filtered to remove any solids, and after 1 week the blue crystals separated. Yield about 32%. 

Fig. 7 The location on tubulin of residues that modulate the sensitivity to MT-destabilizing agents and the location of exogenous inhibitor and nucleotide sites on P tubulin. The a subunit is in semitransparent pink together with a composite P-subunit color-coded as in Fig. 3a with ball-and-stick models of bound taxol (orange), colchicine (yellow) and GDP (magenta). Ball-and-stick models of vinblastine (cyan) are drawn on the two partial vinca sites on a and on P tubulin. The sulfur atom of Cys P12 is highlighted as a yellow sphere. The sites of nine amino acid substitutions [49] that both confer resistance to vinblastine and colchicine and stabilize MTs are depicted as red (on a tubulin) or green (on P tubulin) spheres. Two residues of the P H10 helix whose mutations enhance the sensitivity to colchicine site ligands and destabilize MTs [71] are also shown as blue spheres...

Residues with nonliganding side-chain characteristics that match the amino acid sequences of FVand FVIII with known copper ligands in ceruloplasmin are also presented. Codons for the conserved Leu residue at the position of the axial ligand in the blue copper site of BCB domain 2 of CPs are in parentheses. Residue numbers are for the mature proteins. 

Fig. 2.5 Malcolmia maritima, the color of flower unaltered by metal exposition. Concerning isolated anthocyanes (probably oenin) from grape (Vitis vinifera), the red pigment does not apparently react with Fe(III) in either water or ethanol but turns dark-purple with Cu(II) and yields a blue precipitate with Pb(ll) acetate (Anderson 1924). It also behaves as a pH indicator. The yellowish-green colour observed in live plants thus can be due to superposition of some chlorosis and formation of blue to blue-red (i.e. purple) complexes possibly some third ligand such as an amino acid also contributes...

Redox potentials for the different copper centers in the blue oxidases have been determined for all members of the group but in each case only for a limited number of species. The available data are summarized in Table VI 120, 121). The redox potentials for the type-1 copper of tree laccase and ascorbate oxidase are in the range of 330-400 mV and comparable to the values determined for the small blue copper proteins plastocyanin, azurin, and cucumber basic protein (for redox potentials of small blue copper proteins, see the review of Sykes 122)). The high potential for the fungal Polyporus laccase is probably due to a leucine or phenylalanine residue at the fourth coordination position, which has been observed in the amino-acid sequences of fungal laccases from other species (see Table IV and Section V.B). Two different redox potentials for the type-1 copper were observed for human ceruloplasmin 105). The 490-mV potential can be assigned to the two type-1 copper sites with methionine ligand and the 580-mV potential to the type-1 center with the isosteric leucine at this position (see Section V.B). The... 

The redox states of the flavin cofactor in a purified flavoenzyme can be conveniently studied by optical spectroscopy (see also Elavoprotein Protocols article). Oxidized (yellow) flavin has characteristic absorption maxima around 375 and 450 nm (Fig. lb and Ic). The anionic (red) and neutral (blue) semiquinone show typical absorption maxima around 370 nm and 580 nm, respectively (Fig. lb and Ic). During two-electron reduction to the (anionic) hydroquinone state, the flavin turns pale, and the absorption at 450 nm almost completely disappears (Fig. lb and Ic). The optical properties of the flavin can be influenced through the binding of ligands (substrates, coenzymes, inhibitors) or the interaction with certain amino acid residues. In many cases, these interactions result in so-called charge-transfer complexes that give the protein a peculiar color. 

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