@article {YANG2020120885,
	title = {Characterization of interaction between Bcl-2 oncogene promoter I-Motif DNA and flavonoids using electrospray ionization mass spectrometry and pressure-assisted capillary electrophoresis frontal analysis},
	journal = {Talanta},
	year = {2020},
	pages = {120885},
	abstract = {B-cell lymphoma 2 (Bcl-2) is an antiapoptotic protein which is believed to be a triggering factor in developing human tumors. The Bcl-2 C-rich promoter element has been shown to form the i-motif (IM) via cytosine-cytosine (C{\textendash}C+) base pair building blocks, which can be targeted through the binding of ligands associated with Bcl-2 expression modulation. In this work, we monitored IM development and thermodynamic stability within the Bcl-2 promoter via circular dichroism (CD) spectroscopy and electrospray ionization mass spectrometry (ESI-MS). The results demonstrated that at an acidic pH, as well as in a crowded molecular environment, the Bcl-2 promoter element predominantly exists in a stable intramolecular IM folded state. We further explored the potential of targeting of the Bcl-2 IM to increase chemotherapeutic efficacy. We first used a rapid ESI-MS screening assay to identify possible ligands, finding that three natural flavonoids (P1, P5 and P6) exhibited a clear affinity for IM binding at 1:1 stoichiometry. Relative to P6, P1 and P5 were expected to form the more stable complexes with the Bcl-2 IM in gas phase according to MS/MS data. We further used ESI-MS and pressure-assisted capillary electrophoresis frontal analysis (PACE-FA) to assess the binding constants for these flavonoids in gas and liquid phases, respectively, with the latter considering both specific and non-specific binding. We found P5 and P6 to specifically bind the Bcl-2 IM with binding constants of \~{}104 M-1. P1 binding was confirmed to be due to both specific and nonspecific interactions, and the specific binding constant (8.67 {\texttimes} 103 M-1) was found much less significant than the binding constant in gas phase. Taken all these observations into consideration, the specific binding of selected flavonoids to the Bcl-2 IM may prove to be a potential ligand for modulating Bcl-2 gene expression.},
	keywords = {Bcl-2 oncogene, circular dichroism, Electrospray ionization mass spectrometry, Flavonoids, I-motif, Pressure-assisted capillary electrophoresis frontal analysis},
	issn = {0039-9140},
	doi = {https://doi.org/10.1016/j.talanta.2020.120885},
	url = {http://www.sciencedirect.com/science/article/pii/S0039914020301764},
	author = {Yang Yang and Hengqing Fu and Cheng Qian and Huihui Li and David D.Y. Chen}
}
@article {2182,
	title = {Synthesis, characterisation, and in vitro evaluation of Pro(2)-Ile(3)-S-deoxo-amaninamide and Pro(2)-D-allo-Ile(3)-S-deoxo-amaninamide: Implications for structure-activity relationships in amanitin conformation and toxicity},
	journal = {Chemistry-a European Journal},
	volume = {14},
	number = {11},
	year = {2008},
	note = {ISI Document Delivery No.: 291XITimes Cited: 0Cited Reference Count: 39May, Jonathan P. Fournier, Pierre Patrick, Brian O. Perrin, David M.},
	pages = {3410-3417},
	type = {Article},
	abstract = {The amatoxins are a family of toxic bicyclic peptides that inhibit RNA polymerase II. Herein we discuss an improved synthesis of these compounds from easily obtainable amino acids by means of a solid-phase methodology. Interestingly, we obtained two products of the same mass following our final macrocyclisation, relating to a similar distribution of products described in some previous reports. One of these products was the desired amatoxin; Pro(2)-Ile(3)-S-deoxo-amaninamide 1b. The other compound, after thorough investigation, was confirmed to be the epimer Pro(2)-D-allo-Ile(3)-S-deoxo-amaninamide la, not an atropisomer structure as previously suggested in syntheses of related amanitin analogues. Crystallographic data of la confirms the presence of a beta II-turn, rather than a PI-turn common to the natural toxin and 1b. This difference explains the large variation in CD spectra, although it seems to have relatively little effect on the bioactivity in vitro. These data provide new insights into the bicyclic amatoxin structure.},
	keywords = {ALPHA-AMANITIN, amatoxin, atropisomerism, circular dichroism, CRYSTALLINE STATE, CYCLIZATION, CYSTEINE SULFHYDRYL-GROUPS, EPIMERIZATION, MOLECULAR-STRUCTURE, PEPTIDES, RESOLUTION, RNA-POLYMERASE-II, SERIES, TOXIN BETA-AMANITIN, transcription},
	isbn = {0947-6539},
	url = {<Go to ISI>://000255230200020},
	author = {May, J. P. and Fournier, P. and Patrick, B. O. and Perrin,David M.}
}
@article {935,
	title = {Stereochemical assignment in acyclic lipids across long distance by circular dichroism: Absolute stereochemistry of the aglycone of caminoside A},
	journal = {Angewandte Chemie-International Edition},
	volume = {43},
	number = {44},
	year = {2004},
	note = {ISI Document Delivery No.: 874FTTimes Cited: 14Cited Reference Count: 30},
	pages = {5946-5951},
	type = {Article},
	keywords = {AGENT, ANTIVIRAL ANTIBIOTICS, B-1, CHROMOPHORES, circular dichroism, CONFIGURATION ANALYSIS, CYCLOVIRACIN, glycolipids, LIPOSOMES, MOSHER METHOD, natural products, NMR, PHYSICOCHEMICAL, PROPERTIES, SECONDARY ALCOHOLS, SPIN-COUPLING CONSTANTS, STEREOCHEMISTRY},
	isbn = {1433-7851},
	url = {<Go to ISI>://000225337000017},
	author = {MacMillan, J. B. and Linington, R. G. and Andersen, R. J. and Molinski, T. F.}
}
@article {Funk2004,
	title = {X-ray magnetic circular dichroism of Pseudomonas aeruginosa nickel(II) azurin.},
	journal = {J. Am. Chem. Soc.},
	volume = {126},
	number = {18},
	year = {2004},
	pages = {5859{\textendash}66},
	abstract = {We show that X-ray magnetic circular dichroism (XMCD) can be employed to probe the oxidation states and other electronic structural features of nickel active sites in proteins. As a calibration standard, we have measured XMCD and X-ray absorption (XAS) spectra for the nickel(II) derivative of Pseudomonas aeruginosa azurin (NiAz). Our analysis of these spectra confirms that the electronic ground state of NiAz is high-spin (S = 1); we also find that the L(3)-centroid energy is 853.1(1) eV, the branching ratio is 0.722(4), and the magnetic moment is 1.9(4) mu(B). Density functional theory (DFT) calculations on model NiAz structures establish that orbitals 3d(x2-y2) and 3d(z2) are the two valence holes in the high-spin Ni(II) ground state, and in accord with the experimentally determined orbital magnetic moment, the DFT results also demonstrate that both holes are highly delocalized, with 3d(x2-y2) having much greater ligand character.},
	keywords = {Azurin, Azurin: chemistry, circular dichroism, Circular Dichroism: methods, copper, Copper: chemistry, CRYSTALLOGRAPHY, LIGANDS, Magnetics, models, MOLECULAR, Molecular Conformation, NICKEL, Nickel: chemistry, PDF, Pseudomonas aeruginosa, Pseudomonas aeruginosa: chemistry, X-RAY, X-Rays},
	issn = {0002-7863},
	doi = {10.1021/ja036218d},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/15125678},
	author = {Funk, Tobias and Kennepohl, Pierre and Di Bilio, Angel J and Wehbi, William a and Young, Anthony T and Friedrich, Stephan and Arenholz, Elke and Gray, Harry B and Cramer, Stephen P}
}
@article {3720,
	title = {Multiple pathways for denaturation of horse plasma gelsolin},
	journal = {Biochemistry and Cell Biology-Biochimie Et Biologie Cellulaire},
	volume = {74},
	number = {1},
	year = {1996},
	note = {ISI Document Delivery No.: UE605Times Cited: 1Cited Reference Count: 38},
	pages = {101-107},
	type = {Article},
	abstract = {Gelsolin purified from horse plasma carries a surface charge distribution that greatly influences how the protein unfolds, aggregates, or precipitates as a function of temperature or concentration of chemical denaturant. Modification of gelsolin with fluorescein isothiocyanate replaces positive charges on amine groups with bulky, negatively charged fluorescein moieties. This postpones thermally induced precipitation by about 10 degrees C [Koepf, E.K., and Burtnick, L.D. 1993. Eur. J. Biochem. 212: 713-718]. Interaction with cations such as Ca2+ or guanidinium(+) also alters the surface charge on gelsolin. This affects the structure of the protein in solution, modifies the pathway for unfolding, and moderates the onset of precipitation induced by chemical denaturants or heat. Denaturation of gelsolin is not interpretable in terms of a simple two-state cooperative mechanism. The pathway to a denatured state and intermediate structures present along the way depend upon the agent used to unfold the protein.},
	keywords = {ACTIN-BINDING-SITES, calcium, chemical, circular dichroism, denaturation, FLUORESCEIN ISOTHIOCYANATE, gelsolin, PROTEIN, thermal},
	isbn = {0829-8211},
	url = {<Go to ISI>://A1996UE60500011},
	author = {Koepf, E. K. and Burtnick, L. D.}
}
@article {7352,
	title = {STABILIZATION OF THE STRUCTURE OF HORSE PLASMA VITAMIN-D BINDING-PROTEIN BY DISULFIDE BONDS},
	journal = {Biochemistry and Cell Biology-Biochimie Et Biologie Cellulaire},
	volume = {70},
	number = {1},
	year = {1992},
	note = {ISI Document Delivery No.: HG742Times Cited: 1Cited Reference Count: 27},
	month = {Jan},
	pages = {10-15},
	type = {Article},
	abstract = {Vitamin D binding protein (DBP) was isolated from horse plasma in a four-step procedure that involved Affi-Gel Blue affinity chromatography, gel filtration, hydroxylapatite chromatography, and anion exchange high-pressure liquid chromatography. The yield of DBP from 80 mL of plasma was 6-7 mg. Horse plasma DBP closely resembles other plasma DBPs, being a tryptophan-free protein of M(r) 53 000. It is able to bind to and block the polymerization of monomeric actin. The secondary structure of DBP was calculated from circular dichroism measurements to be 39\% alpha-helix, 42\% beta-sheet, and 19\% random coil. Circular dichroism and fluorescence studies revealed that the disulfide bonds of DBP contribute substantial structural stabilization to the molecule with respect to thermal denaturation. The thermal stability of DBP can be used to advantage. Incorporation of a brief treatment at 70-degrees-C into the preparative scheme enables omission of one chromatographic step, without detectable alteration of the purified product.},
	keywords = {actin, circular dichroism, CIRCULAR-DICHROISM, COMPLEX, denaturation, DISULFIDE BONDS, FLUORESCENCE, GC-GLOBULIN, POLYMERIZATION, RAT, SERUM, thermal, TROPOMYOSIN, VITAMIN-D BINDING PROTEIN},
	isbn = {0829-8211},
	url = {<Go to ISI>://A1992HG74200002},
	author = {Robinson, R. C. and Burtnick, L. D.}
}
