Circular dichroism of bilirubin‐human serum albumin complexes in aqueous solution

Blauer, G.; Harmatz, D.; Naparstek, A.

doi:10.1016/0014-5793(70)80309-x

Cited by 44 publications

(14 citation statements)

References 5 publications

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“…HSA possesses a single high-affinity binding site for heme [40,41] near the hydrophobic cavity of subdomain IIA [42,43]. The heme-HSA adduct has a characteristic Soret absorption at 405 nm with an intensity that depends on the amount of heme bound to the protein, which can be modified by drugs capable of competing for that site.…”

Section: Resultsmentioning

confidence: 99%

Interactions of arene–Ru(II)–chloroquine complexes of known antimalarial and antitumor activity with human serum albumin (HSA) and transferrin

Martínez

Suárez

Shand

et al. 2011

Journal of Inorganic Biochemistry

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The interactions of π-arene-Ru(II)-chloroquine complexes with human serum albumin (HSA), apotransferrin and holotransferrin have been studied by circular dichroism (CD) and UV-Visible spectroscopies, together with isothermal titration calorimetry (ITC). The data for [Ru(η6-p-cymene)(CQ)(H2O)Cl]PF6 (1), [Ru(η6-benzene)(CQ)(H2O)Cl]PF6 (2), [Ru(η6-p-cymene)(CQ)(H2O)2][PF6]2 (3), [Ru(η6-p-cymene)(CQ)(en)][PF6]2 (4), [Ru(η6-p-cymene)(η6-CQDP)][BF4]2 (5) (CQ: chloroquine; DP: diphosphate; en: ethylenediamine), in comparison with CQDP and [Ru(η6-p-cymene)(en)Cl][PF6] (6) as controls demonstrate that 1, 2, 3, and 5, which contain exchangeable ligands, bind to HSA and to apotransferrin in a covalent manner. The interaction did not affect the α-helical content in apotransferrin but resulted in a loss of this type of structure in HSA. The binding was reversed in both cases by a decrease in pH and in the case of the Ru-HSA adducts, also by addition of chelating agents. A weaker interaction between complexes 4 and 6 and HSA was measured by ITC but was not detectable spectroscopically. No interactions were observed for complexes 4 and 6 with apotransferrin or for CQDP with either protein. The combined results suggest that the arene-Ru(II)-chloroquine complexes, known to be active against resistant malaria and several lines of cancer cells, also display a good transport behavior that makes them good candidates for drug development.

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Section: Resultsmentioning

confidence: 99%

Interactions of arene–Ru(II)–chloroquine complexes of known antimalarial and antitumor activity with human serum albumin (HSA) and transferrin

Martínez

Suárez

Shand

et al. 2011

Journal of Inorganic Biochemistry

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“…Firstly, it must be pointed out that some toxins may bind to albumin in different molar ratios: it is generally agreed that the albumin molecule has one high affinity and one (or two) low affinity binding sites for bilirubin [19,20]; also for tryptophan, an analogous multiplicity of binding sites seems to exist [21][22][23]. Anyway, binding constants to secondary sites are in general much lower than those of the primary site (values of 5 − 7 × 10 7 M −1 and 4 − 5 × 10 6 M −1 are reported in literature for the binding constants of bilirubin to the first and second site of human serum albumin, respectively [19,20]), therefore, at least for high albumin-totoxin molar ratios in the liquid phase, formation of complexes involving secondary sites may be neglected.…”

Section: Mathematical Modelmentioning

confidence: 99%

Bilirubin and tryptophan adsorption in albumin-containing solutions

Annesini

Carlo

Piemonte

et al. 2008

Biochemical Engineering Journal

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“…Cells of 1.0 em optical path were used for all CD measurements. As in previous work [4][5][6][7] , no Lorentz field corrections were applied.…”

Section: Preparation Of Solutionsmentioning

confidence: 99%

“…[2, p.27D]). Recently, the optical activity of the bound bilirubin has been extensively investigated by measurement of ORD [3] and CD [4][5][6][7][8]. With the aid of computer analysis of both light-absorption and dichroic bands, an exciton splitting mechanism involving electric transition dipole moments of the two dipyrromethene chromophores was used for interpretation of the main results obtained in the visible region [6] (see also, for example, [9]).…”

Section: Introduction *mentioning

confidence: 99%

Biopolymer — Small Molecule Interactions. Optical Properties of the System Biliverdin‐Serum Albumin in Aqueous Medium

Blauer

Zvilichovsky

1973

Israel Journal of Chemistry

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Circular dichroism (CD) and light‐absorption measurements in the wavelength range 300 to 650 nm were carried out for complexes of biliverdin (∼ 2.5 × 10−5 M) with either bovine or human serum albumin (charcoal treated) in aqueous solution (25–27°C) at several protein concentrations and pH values in the range 4 to 10. In all cases investigated, two large ellipticity bands were measured near 385 nm and about 650 nm, respectively, which were of opposite sign. In addition, two smaller bands near 300 and 535 nm were resolved by computer analysis into Gaussian curves of the CD spectrum of biliverdin‐human serum albumin complexes. The main CD bands were inverted in their sign in biliverdin‐bovine serum albumin complexes when compared at pH 5 and 10. Under the conditions used, free biliverdin did not show significant optical activity. The optical activity observed for the complexes is attributed to electric transition dipole coupling of biliverdin with protein transitions and to possible formation of skewed conformations of the biliverdin chromophore upon binding, leading to inherent dissymmetry. Unlike the corresponding bilirubin complexes investigated previously, there appears to be no evidence for substantial band splitting in the small molecule occurring upon binding to the biopolymer. Thus the presence of a center methene bridge instead of an isolating methylene group, the latter allowing internal rotation in the bile pigment, appears largely to determine the mechanism of generation of optical activity. In the case of bilirubin and at excess serum albumin, the observed optical activity is considered to be due mainly to exciton coupling between electric transition dipole moments of the dipyrromethene chromophores within the asymmetrically bound bilirubin. The optical properties investigated may serve as a very sensitive measure of the different types of interaction between the biopolymer and the small conjugated molecule which result from structural and conformational differences of the molecules participating in complex formation.

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Circular dichroism of bilirubin‐human serum albumin complexes in aqueous solution

Cited by 44 publications

References 5 publications

Interactions of arene–Ru(II)–chloroquine complexes of known antimalarial and antitumor activity with human serum albumin (HSA) and transferrin

Interactions of arene–Ru(II)–chloroquine complexes of known antimalarial and antitumor activity with human serum albumin (HSA) and transferrin

Bilirubin and tryptophan adsorption in albumin-containing solutions

Biopolymer — Small Molecule Interactions. Optical Properties of the System Biliverdin‐Serum Albumin in Aqueous Medium

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