Helical conformation of amylose in aqueous solution. I. Viscosity measurements

Biopolymers ◽  
2007 ◽  
Vol 23 (11) ◽  
pp. 2525-2542 ◽  
Author(s):  
Hans Elmgren
Keyword(s):  
Aqueous Solution ◽  
Helical Conformation ◽  
Viscosity Measurements

Oligopeptide-porphyrin interactions studied by circular dichroism spectroscopy: the effect of metalloporphyrin axial ligands on peptide matrix conformation

2008 ◽  
Vol 12 (12) ◽  
pp. 1270-1278 ◽  
Author(s):  
Vladimír Setnička ◽  
Jan Hlaváček ◽  
Marie Urbanová
Keyword(s):  
Aqueous Solution ◽  
Circular Dichroism ◽  
Conformational Changes ◽  
Helical Conformation ◽  
Compact Structure ◽  
Axial Ligands ◽  
Metal Derivatives ◽  
Derivatives Of ◽  
Circular Dichroïsm ◽  
Β Sheet

Vibrational (VCD) and electronic circular dichroism (ECD) spectroscopies were used to investigate non-covalent interactions between the cationic tripeptide L-lysyl-L-alanyl-L-alanine (KAA) and the anionic porphyrin meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) in aqueous solution. Also studied were the interactions between KAA and the three metal derivatives of TPPS (copper(II), iron(III), and manganese(III)), each of which has a different number of axial ligands. VCD spectra in the amide I' ( C = O stretching vibration) region are extremely sensitive to peptide conformation, and, consequently, provide direct information about the conformational changes of host oligopeptide matrices caused by electrostatic interaction with guest porphyrin molecules. We found that pure KAA adopts a left-handed polyproline II (PPII) helical conformation when dissolved in aqueous solution at near-neutral pH values. When mixed with metal-free TPPS under the same conditions, VCD intensities were markedly reduced in the amide I' region and a new negative band was observed at 1634 cm−1; both findings indicating the transition of the PPII conformation into a less compact structure having similarities to β-sheet, herein termed a β-sheet-like conformation. In the case of the metal derivatives of TPPS studied, only variations in the VCD intensities in the amide I' region were observed. Compared to the results for pure KAA, the binding of Cu (II) TPPS , which has no axial ligand, resulted in the greatest decrease in amide I' VCD intensity. Nevertheless, the shape of a VCD spectrum characteristic for a PPII conformation was maintained, thereby indicating the presence of an “extended” PPII conformation in the Cu (II) TPPS -KAA complex. Conversely, Mn (III) TPPS , which has two axial ligands, did not significantly affect the PPII conformation of KAA in the Mn (III) TPPS -KAA complex. The effects of the metalation and axial ligation of TPPS on the conformation of KAA in peptide-porphyrin complexes are discussed, together with the results of our ECD study.

Protamines. VII. Circular Dichroism Study of Salmine A I

1981 ◽  
Vol 36 (3-4) ◽  
pp. 305-309 ◽  
Author(s):  
G. M. Bonora ◽  
F. Bertanzon ◽  
V. Moretto ◽  
C. Toniolo
Keyword(s):  
Aqueous Solution ◽  
Circular Dichroism ◽  
Statistical Methods ◽  
Basic Protein ◽  
Helical Conformation ◽  
Counter Ions ◽  
Conformational Preferences ◽  
Main Components ◽  
The Right ◽  
Circular Dichroïsm

Salmine A I, one of the components of the protamine from salmon, has been purified and characterized. The conformational preferences of salmine A I have been examined as a function of pH, added salts, presence of helix-supporting solvents, and temperature, using circular dichroism. It has been found that this small basic protein adopts predominantly an unordered conformation in aqueous solution. Addition of counter-ions, in particular perchlorate, and 2-chloroethanol induces to various extents the onset of the right-handed α-helical conformation. The results are discussed in comparison with those previously reported on the three main components of clupeine, the protamine from herring, and with the published conformational predictions by various statistical methods

scholarly journals Crystal structure of metallo-DNA duplex containing T-Hg(II)-T base pairs

2014 ◽  
Vol 70 (a1) ◽  
pp. C1375-C1375
Author(s):  
Jiro Kondo ◽  
Tom Yamada ◽  
Chika Hirose ◽  
Itaru Okamoto ◽  
Yoshiyuki Tanaka ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Nucleic Acid ◽  
Helical Conformation ◽  
Helical Axis ◽  
Dna Duplex ◽  
Base Pairs ◽  
Imino Proton ◽  
Sensing System ◽  
Hybrid Duplex

The DNA duplex containing mercury-mediated base pairs (T-Hg(II)-T) is an attractive biomacromolecular nanomaterials. In a recent study, it was confirmed that the Hg(II) ion significantly stabilizes a DNA duplex by binding selectively to a T-T mispair [1]. Based on the phenomenon observed, a DNA-based sensing system that selectively and sensitively detects Hg(II) ions in aqueous solution was developed [2]. In the present study, we have solved the first crystal structure of a B-form DNA duplex containing two consecutive T-Hg(II)-T base pairs [3]. The Hg(II) ion occupies the center between two T residues. The geometry of the T-Hg(II)-T base pair is very similar to that of the canonical Watson-Crick base pairs. The distance of N3-Hg(II) bond is 2.0 Å, suggesting that the N3 nitrogen releases an imino-proton even at neutral pH (pKa of N3 position of T is 9.8) and directly bonds to Hg(II). In the B-form DNA, the helical axis runs through the center of base pairs, and the Hg(II) ions are therefore aligned along the helical axis. The distance between the two neighboring Hg(II) ions is 3.3 Å. The relatively short Hg(II)-Hg(II) distance indicates that the metallophilic attraction could exit between them and may stabilize the B-form duplex. To support this, the DNA duplex is largely distorted and adopts an unusual non-helical conformation in the absence of Hg(II). In conclusion, the Hg(II) ion is essential for maintaining the B-form conformation of the DNA duplex containing T-T mispairs. The structure of the Hg(II)-DNA hybrid duplex itself and the Hg(II)-induced structural switching from the non-helical form to the B-form provide the basis for the structure-based design of metal-conjugated nucleic acid nanomaterials.

scholarly journals Study of Bovine Serum Albumin Solubility in Aqueous Solutions by Intrinsic Viscosity Measurements

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Martin Alberto Masuelli
Keyword(s):  
Aqueous Solution ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Intrinsic Viscosity ◽  
Conformational Changes ◽  
Bovine Serum ◽  
Experimental Measurements ◽  
Viscosity Measurements ◽  
The Relationship

The behavior of bovine serum albumin (BSA) in water is scarcely studied, and the thermodynamic properties arising from the experimental measurements have not been reported. Intrinsic viscosity measurements are very useful in assessing the interaction between the solute and solvent. This work discussed in a simple determination of the enthalpy of BSA in aqueous solution when the concentration ranges from 0.2 to 36.71% wt. and the temperature from 35 to 40°C. The relationship between the concentration and intrinsic viscosity is determined according to the method of Huggins. The temperature increase reduces the ratio between inherent viscosity and concentration (ηi/c). This is reflected in the Van't Hoff curve. Furthermore, this work proposes hydrodynamic cohesion value as an indicator of the degree of affinity of protein with water and thermodynamic implications in conformational changes.

Correlation between the antitumor activity of a polysaccharide schizophyllan and its triple-helical conformation in dilute aqueous solution

1983 ◽  
Vol 17 (4) ◽  
pp. 337-342 ◽  
Author(s):  
Toshio Yanaki ◽  
Wataru Ito ◽  
Kengo Tabata ◽  
Takemasa Kojima ◽  
Takashi Norisuye ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Antitumor Activity ◽  
Helical Conformation ◽  
Dilute Aqueous Solution
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