Studies of interaction between iron (III) and intermediates of synthetic neuromelanin by means of cyclic voltammetry of Fe(CN)(3-)(6) and dopamine

Neuromelanin is a complex polymer pigment found primarily in the dopaminergic neurons of the human substantia nigra, whose composition is complex including production of dopamine auto-oxidation, glutathione and a variety of amino acid. Neuromelanin forms stable complex with iron (111). We observed that 5,6-dihydroxyindole and its ramification possessed strong ability of chelating iron (111), and they are the production of dopamine auto-oxidation under physiological pH condition. In the present Of L-Cysteine, the relative yields of electrochemical oxidation of dopamine also had strong ability of chelating iron (111). The experimental results suggest that 5,6-dihydroxyindole and 5-S-cysteineldopamine play important roles in the process of synthetic neuromelanin chelating iron (111).

Studies on the interaction of porphyrin with antibody with fluorescent spectrum and UV-Vis differential spectra

After meso-tetra (alpha, alpha, alpha, alpha-O-phenylacetyl benzene)porphyrin combined with McAb 1F2, there was a significant hyperchromic effect, indicating that the combination of porphyrin and antibody is rigid and compact, aromatic amino acids exist at the combining sites of antigen in antibody. These aromatic amino acids are Trys and Trps, but the numbers of Trp are more than that found for Trys. The stochiometric ratio of porphyrin to 1F2 is 1:1, the disassociation constant was determined as(2.084+/-0.216) x 10(-10) mol/L by a method of fluorescence quenching, showing that both have a high affinity.

Studies on the interaction of rare earth ions with BSA

Studies on the bounding character of rare earth ions with borine serum albumin(BSA) are significant for understanding the state of rare earth ions in body and their effects on the structure and function of protein. The fluorescence spectrum and pH potentiometry showed consistent results of apparent complexion constant of Tb-2 . BSA. The equilibrium dialysis showed that there are two specific binding sites and more than six non-specific binding sites of RE ions onto BSA molecule with the conditional stable constants lg K-1 = 5. 157 and lgK(2) = 3. 435. Na-23 NMR studies revealed that the BSA peptide chain bound to RE ions was expanded and the mobility of its molecular backbone was increased.

Studies on plant calmodulin and its interaction with antagonist W-7 by Ln(3+) luminescence probes

Plant calmodulin (CaM) has been extracted from cauliflower, and the purified CaM has been identified with the activation of NAD kinase (NADK) and the inhibition effect of CaM antagonist W-7. CaM's intrinsic fluorescence and Tb3+ fluorescence showed that there was one tyrosine residue and four metal-binding sites in cauliflower CaM. Based on Forster-type nonradiative energy theory, the distances of Tyr --> site III, IV have been determined, and these are 1.23 nm (Tyr --> site III ) and 1.18 nm(Tyr --> site IV). The Eu3+ and Tb3+ fluorescence probes showed that the combination of CaM with W-7 resulted in significant change on CaM's conformation, but did not affect coordination environment of metal-binding sites.

Studies of catalyzed reaction mechanism between co-polyether (THF/EO) and N-100 by NMR - Interaction and complex formation between reactants and catalysts

To elucidate the mechanism of the catalyzed reaction of co-polyether (EO/THF) with N-100, the interaction and complex formation between reactants and catalysts were investigated by means of NMR spectroscopy. It is shown that the resonance peak of isocyanate carbon splits into two parts when the solutions of N-100 and co-polyether were mixed. The disappearing of proton resonance peak of hydroxyl group in NMR spectra when dibutyltin dilaurate(DBTDL) were added to the copolyether(THF/EO) solution indicates the complex formation, This interaction appears to be a bonding of tin to the oxygen of hydroxyl and make the hydrogen of the hydroxyl group very mobile and active, then exchange with other protons, In the case of triphenyl bismuth(TPB), the high field shift and intensity enhancement of proton peak were observed, which suggest a nucleophilic attack of the bismuth to the hydroxyl hydrogen.

2D NMR and FT-Raman spectroscopic studies on the interaction of lanthanide ions and Ln-DTPA with phospholipid bilayers

The interactions of lanthanide ions and the Ln-DTPA (DTPA = diethylenetriaminepentaacetate) complex with di palmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine (DPPE) bilayers are studied by 2D NOESY and FT-Raman spectroscopy. Proton NMR spectroscopic results show that lanthanide ions combine with phosphate groups in the polar region of the outer layer of DPPC liposomes, leading to the separation in chemical shift of the proton signal of N(CH3)(3) The conformational change of the O-C-C-N+ backbone from the gauche conformer to the trans one is not found; i.e., the orientation of the polar headgroup is still parallel to the surface of the bilayers. The Ln-DTPA complex at low concentration in a pH 7.4 solution localizes far away from bilayers and thereby has little effect on the structure of bilayers. The FT-Raman spectroscopic results indicate that lanthanide ions affect strongly the fluidity of acyl chains of DPPE bilayers while the Ln-DTPA complex affects it slightly.

NMR and FT-Raman studies on the interaction of lanthanide ions with sphingomyelin bilayers

The interactions of lanthanide ions with sphingomyelin bilayers have been studied by using 2D NOESY spectroscopy and FT-Raman spectroscopy methods. The results indicate that lanthanide ions, as well as divalent calcium, combine mainly to the phosphate group in the polar headgroup and do not change the conformation of O-C-C-N+ backbone in the choline group of sphingomyelin bilayers. The polar headgroup is still extending parallel to the bilayer surface and O-C-C-N+ group is still in its gauche conformer.

FT-RAMAN SPECTROSCOPIC STUDIES ON THE INTERACTION OF METAL-IONS WITH SPHINGOMYELIN BILAYER

The interaction of trivalent lanthanide ions and divalent calcium ions with sphingomyelin bilayer has been studied by FT-Raman spectroscopy. The results showed that the bonding of metal ions to the phosphate group of sphingomyelin bilayer, either La3+ or Ca2+, did not change the conformation of the choline group, that is, O-C-C-N+ is still in its gauche conformation. The presence of metal ions changed the states of the interfacial region from liquid-like to amorphous state and even to crystalline. They increased the fluidity of acyl chains of sphingomyelin bilayer and made them packed disorderly.

CALCULATIONS OF THE EIGENVALUES OF PURE QUADRUPOLE INTERACTION IN MOSSBAUER-EFFECT STUDIES

Two approximate formulae to calculate the eigenvalues of pure quadrupole interaction in Mossbauer effect studies have been proposed and the eigenvalue coefficients in the formulae have been given for various excited states and ground states of the nucleus with different spin. All the eigenvalues of pure quadrupole interaction between both excited state and ground state of nucleus with spin I = 3/2 divided-by 9/2 and the electric-field gradient with different asymmetry parameter (eta = 0 divided-by 1.0) have been calculated by these formulae. The results show that the accuracies in all the calculations are more satisfactory or same in comparison with those obtained by the formula of Shenoy and Dunlap, especially when the asymmetry parameter of electric-field gradient is larger than 0.8 for the nucleus with spin I = 5/2.

Predicting protein interaction interfaces from protein sequences: Case studies of subtilisin and phycocyanin

Identification of protein interaction interfaces is very important for understanding the molecular mechanisms underlying biological phenomena. Here, we present a novel method for predicting protein interaction interfaces from sequences by using PAM matrix (PIFPAM). Sequence alignments for interacting proteins were constructed and parsed into segments using sliding windows. By calculating distance matrix for each segment, the correlation coefficients between segments were estimated. The interaction interfaces were predicted by extracting highly correlated segment pairs from the correlation map. The predictions achieved an accuracy 0.41-0.71 for eight intraprotein interaction examples, and 0.07-0.60 for four interprotein interaction examples. Compared with three previously published methods, PIFPAM predicted more contacting site pairs for 11 out of the 12 example proteins, and predicted at least 34% more contacting site pairs for eight proteins of them. The factors affecting the predictions were also analyzed. Since PIFPAM uses only the alignments of the two interacting proteins as input, it is especially useful when no three-dimensional protein structure data are available.

DNA interaction and cytotoxicity studies of new ruthenium(II) cyclopentadienyl derivative complexescontaining heteroaromatic ligands

Four ruthenium(II) complexes with the formula [Ru(eta(5)-C(5)H(5))(PP)L][CF(3)SO(3)], being (PP = two triphenylphosphine molecules), L = 1-benzylimidazole, 1; (PP = two triphenylphosphine molecules), L = 2,2'bipyridine, 2; (PP = two triphenylphosphine molecules), L = 4-Methylpyridine, 3; (PP = 1,2-bis(diphenylphosphine) ethane), L = 4-Methylpyridine, 4, were prepared, in view to evaluate their potentialities as antitumor agents. The compounds were completely characterized by NMR spectroscopy and their crystal and molecular structures were determined by X-ray diffraction. Electrochemical studies were carried out giving for all the compounds quasi-reversible processes. The images obtained by atomic force microscopy (AFM) suggest interaction with pBR322 plasmid DNA. Measurements of the viscosity of solutions of free DNA and DNA incubated with different concentrations of the compounds confirmed this interaction. The cytotoxicity of compounds 1234 was much higher than that of cisplatin against human leukemia cancer cells (HL-60 cells). IC(50) values for all the compounds are in the range of submicromolar amounts. Apoptotic death percentage was also studied resulting similar than that of cisplatin. (C) 2010 Elsevier Inc. All rights reserved.