Synthesis of the native copper(II)-transport site of human serum albumin and its copper(II)-binding properties

Iyer, K.S.N.; Lau, Show‐Jy; Laurie, Stuart H.; Sarkar, Bibudhendra

doi:10.1042/bj1690061

Cited by 64 publications

(17 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reported conditional dissociation constant of GHK and analogues of DAHK are about 1 x 10 -14 M [19,20,[31][32][33][34][35][36]. Although in a 100mM HEPES buffer the affinity will decrease to a app Kd of about 10 -12 M at pH 7.4 [26], this affinity is still too high to be measured directly by ITC.…”

Section: Resultsmentioning

confidence: 97%

Thermodynamic study of Cu2+ binding to the DAHK and GHK peptides by isothermal titration calorimetry (ITC) with the weaker competitor glycine

et al. 2011

View full text Add to dashboard Cite

The peptides Asp-Ala-His-Lys (DAHK) and Gly-His-Lys (GHK) are naturally occurring copper(II)-chelating motives in human serum and cerebrospinal fluid. Here the sensitive thermodynamic technique isothermal titration calorimetry (ITC) has been used to study the energetics of copper(II) binding to DAHK and GHK peptides in the presence of the weaker ligand glycine as a competitor. DAHK and GHK bind Cu(II) predominantly in a 1:1 stoichiometry with conditional dissociation constants (i.e. at pH 7.4, in the absence of the competing chelators glycine and HEPES buffer) of 2.6 +/-0.4 x 10 -14 M and of 7.0 +/-1.0 x 10 -14 M, respectively. Furthermore, the apparent ΔH values were measured and the number of protons released upon Cu(II) binding was determined by performing experiments in different buffers. This allowed us to determine the conditional ΔG, ΔH, and ΔS, i.e. corrected for the contributions of the weaker ligand glycine and the buffer at pH 7.4. We found that the entropic and enthalpic contributions to the Cu(II)-binding to GHK and DAHK are distinct, with a higher enthalpic contribution for GHK. The obtained thermodynamic parameters correspond well to those in the literature obtained by other techniques, suggesting that the use of the weaker ligand glycine as a competitor in ITC provides accurate data for Cu(II)-binding to high affinity peptides, which cannot be accurately determined without the use of a competitor ligand.3

show abstract

Section: Resultsmentioning

confidence: 97%

Thermodynamic study of Cu2+ binding to the DAHK and GHK peptides by isothermal titration calorimetry (ITC) with the weaker competitor glycine

et al. 2011

View full text Add to dashboard Cite

show abstract

“…In fact, 20 M CuCl 2 was almost ineffective to induce hemolysis (data not shown). In relation to the suppression of copper-induced cell damage by S100b protein, it should be noted that serum albumin, known to tightly bind copper ions (19), likewise exerts inhibitory effects on various oxidative processes involving copper ions. Among such processes are L-ascorbate oxidation catalyzed by copper salt (20) and the hemolysis induced by copper salt alone (12) or by copper salt plus Lascorbate (21).…”

Section: Discussionmentioning

confidence: 99%

Identification of S100b Protein as Copper-binding Protein and Its Suppression of Copper-induced Cell Damage

Nishikawa

Lee

Shiraishi

et al. 1997

Journal of Biological Chemistry

View full text Add to dashboard Cite

We have isolated from bovine brain a protein with a high capacity to inhibit the copper ion-catalyzed oxidation of L-ascorbate and identified it as S100b protein, an EF-hand calcium-binding protein, by sequencing its proteolytic peptides. Copper binding studies showed that this protein has four copper-binding sites per dimeric protein molecule with a dissociation constant of 0.46 M and that in the presence of L-ascorbate, copper ions bind to a total of six binding sites with a great increase in affinity. Furthermore, we examined whether S100b protein can prevent copper-induced cell damage. Bovine S100b protein was found to suppress dose-dependently the hemolysis of mouse erythrocytes induced by CuCl 2 . We transformed Escherichia coli cells with pGEX-5X-3 vector containing a cDNA for rat S100b protein, so that this protein could be expressed as a fusion protein with glutathione S-transferase. The transformed cells were demonstrated to be markedly resistant to a treatment with CuCl 2 plus H 2 O 2 as compared with the control cells expressing glutathione S-transferase alone. These results indicate that S100b protein does suppress oxidative cell damage by sequestering copper ions.

show abstract

“…the imidazole nitrogen of a histidine sidechain, the mercaptide sulfur as demonstrate by Suguira for several SH-containing peptides [571, or an amino nitrogen. Amongst these prosthetic groups the imidazole moiety plays an unique role as shown by the pronounced Cu(I1) specificity of human albumin [58] (with a histidine in position 3 of the N-terminal domain) compared to the non-specific binding of Cu(TT) in the case of dog albumin, where a tyrosine residue substitutes for histidine-3 [59]. The preference of N-terminal binding over C-terminal binding of Cu( 11) by these macromolecules is confirmed by our amide model complexes, which show that the COO-function alone can not serve as a potent primary site for Cu (11) to promote NHCO ionisation.…”

Section: Discussionmentioning

confidence: 99%

Model Studies on the Coordination of Copper in Biological Systems. The Deprotonated Peptide Nitrogen as a Potential Binding Site for Copper(II)

Kroneck

Vortisch²,

Hemmerich

1980

Eur J Biochem

View full text Add to dashboard Cite

1. A large number of potentially bidentate and tridentate amides, X-Y-CONH-Z, were used as model ligands to investigate the complex formation of Cu(1I) with the deprotonated peptide nitrogen in biological molecules. A combination of potentiometric titration, spectrophotometry and electron paramagnetic resonance was applied to analyse the structure of the Cu(I1) chelates formed at neutral and basic pH.2. By systematic variation of the primary binding function X, the ring size of the chelate, and the spatial properties of the C-terminal and N-terminal substituents, three classes of amide ligands could be established with reference to their capacity for Cu(I1)-induced deprotonation of NHCO and metal binding.3. Under physiological conditions of pH, peptide (class A) chelates are only formed by those bidentate amide ligands with X being either an imidazole (sp2) nitrogen or a terminal (sp3) amino nitrogen. Mercaptide sulfur must also be considered to belong in this group of strong copper(I1)-binding sites, but in our low-molecular-weight model ligands the redox equilibrium 2 Cu(I1) + 2 RSH Z 2 Cu(1) + RSSR + 2 H f interferes, yielding insoluble Cu(1)-S polymers above pH 4. In addition to the unidentate binding strength of X, entropy effects play an important role. Depending on whether X is an imidazole or amino nitrogen, only five-membered or sixmembered monocyclic chelate structures respectively cause coordination of the deprotonated peptide function.4. Biuret (class B) Cu(I1) chelates are only formed under non-physiological conditions at pH > 11.5 producing the well known violet chromophores Cu"N4. In general these complexes, which also include the Cu(I1) biguanides, show a clearly resolved electron paramagnetic resonance spectrum with nitrogen superhyperfine structure.5. A third class of peptide model ligands (class C) consists of those amides where the Cu"-X bond does not provide enough thermodynamic stability. The binding site of these class C amides includes functional groups such as carboxylate (COO-), methionine sulfur (RSR'), aliphatic or aromatic hydroxyl (OH) and amide nitrogen (NHCO) itself. When X is a pyridine (sp2) nitrogen or an amino (sp3) nitrogen, NHCO deprotonation is only promoted in five-membered but not six-membered ring chelates. On the other hand, a combination of COO-and NH2, as in asparagine, will allow deprotonation of NHCO in the presence of Cu(I1). And third, despite a pronounced unidentate affinity of the imidazole nitrogen for Cu(II), N-acetylhistamine acts as a class C amide, in contrast to imidazolylacetamide, which forms a stable Cu(I1) peptide chelate. This difference in Cu binding is explained on the basis of space-filling models. These clearly demonstrate that in the case of the 2 : l complex of Cu(I1) with N-acetylhistamine, the planarity of the ionised peptide function can not be retained in a square planar arrangement of the two amide ligands around the copper center.Over the past two decades copper-containing bioazurin have been successfully analysed by X-ray crystallography ...

show abstract

Synthesis of the native copper(II)-transport site of human serum albumin and its copper(II)-binding properties

Cited by 64 publications

References 22 publications

Thermodynamic study of Cu2+ binding to the DAHK and GHK peptides by isothermal titration calorimetry (ITC) with the weaker competitor glycine

Thermodynamic study of Cu2+ binding to the DAHK and GHK peptides by isothermal titration calorimetry (ITC) with the weaker competitor glycine

Identification of S100b Protein as Copper-binding Protein and Its Suppression of Copper-induced Cell Damage

Model Studies on the Coordination of Copper in Biological Systems. The Deprotonated Peptide Nitrogen as a Potential Binding Site for Copper(II)

Contact Info

Product

Resources

About