The optical properties of α2-macroglobulin from normal and from cystic fibrosis plasma

1981 ◽  
Vol 59 (7) ◽  
pp. 519-523 ◽  
Author(s):  
Janice B. Y. Richman ◽  
Jacob A. Verpoorte
Keyword(s):  
Cystic Fibrosis ◽  
Optical Properties ◽  
Fluorescence Spectra ◽  
Molar Ratios ◽  
Normal Individuals ◽  
Α2 Macroglobulin ◽  
Tryptophan Residues ◽  
Sheet Structure ◽  
Α Helix ◽  
Β Sheet

The α2-macroglobulin (α2-M) was purified from the plasma of normal individuals and from that of cystic fibrosis patients. The proteins exhibited identical optical properties. Both proteins have an absorbance coefficient of A = 1060 g∙cm−2 at 280 nm. The circular dichroism spectra are identical and indicate about 45% β-sheet structure and almost no α-helix. The spectra of solutions at pH 8.0 do not change when trypsin is added.The fluorescence spectra of the α2-M measured at pH 8.0 have contributions by tyrosine and tryptophan residues. The fluorescence intensities are identical and are enhanced about 30% when trypsin is added in 2:1 molar ratios.

scholarly journals Raman Evidence of p53-DBD Disorder Decrease upon Interaction with the Anticancer Protein Azurin

2019 ◽  
Vol 20 (12) ◽  
pp. 3078 ◽  
Author(s):  
Sara Signorelli ◽  
Salvatore Cannistraro ◽  
Anna Rita Bizzarri
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Principal Component ◽  
Intrinsically Disordered Protein ◽  
Random Coil ◽  
Disordered Proteins ◽  
Conformational Heterogeneity ◽  
Intrinsically Disordered ◽  
Tryptophan Residues ◽  
Α Helix ◽  
Β Sheet

Raman spectroscopy, which is a suitable tool to elucidate the structural properties of intrinsically disordered proteins, was applied to investigate the changes in both the structure and the conformational heterogeneity of the DNA-binding domain (DBD) belonging to the intrinsically disordered protein p53 upon its binding to Azurin, an electron-transfer anticancer protein from Pseudomonas aeruginosa. The Raman spectra of the DBD and Azurin, isolated in solution or forming a complex, were analyzed by a combined analysis based on peak inspection, band convolution, and principal component analysis (PCA). In particular, our attention was focused on the Raman peaks of Tyrosine and Tryptophan residues, which are diagnostic markers of protein side chain environment, and on the Amide I band, of which the deconvolution allows us to extract information about α-helix, β-sheet, and random coil contents. The results show an increase of the secondary structure content of DBD concomitantly with a decrease of its conformational heterogeneity upon its binding to Azurin. These findings suggest an Azurin-induced conformational change of DBD structure with possible implications for p53 functionality.

Post-assembly α-helix to β-sheet structural transformation within SAF-p1/p2a peptide nanofibers

Soft Matter ◽  
2018 ◽  
Vol 14 (44) ◽  
pp. 8986-8996 ◽  
Author(s):  
Evan K. Roberts ◽  
Kong M. Wong ◽  
Elizabeth J. Lee ◽  
Melina M. Le ◽  
Dipam M. Patel ◽  
...  
Keyword(s):  
Structural Transformation ◽  
Coiled Coils ◽  
Peptide Nanofibers ◽  
Sheet Structure ◽  
Peptide System ◽  
Α Helix ◽  
Β Sheet

The SAF-p1/p2a binary peptide system co-assembles in water into α-helical coiled coils, but can convert post-assembly into a β-sheet structure.

scholarly journals Comparison of α-Helix and β-Sheet Structure Adaptation to a Quantum Dot Geometry: Toward the Identification of an Optimal Motif for a Protein Nanoparticle Cover

ACS Omega ◽  
2019 ◽  
Vol 4 (8) ◽  
pp. 13086-13099 ◽  
Author(s):  
Katarzyna Kopeć ◽  
Marta Pędziwiatr ◽  
Dominik Gront ◽  
Olga Sztatelman ◽  
Jakub Sławski ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Sheet Structure ◽  
Structure Adaptation ◽  
Α Helix ◽  
Β Sheet

scholarly journals Multispectroscopic Study of the Interaction of Chloramphenicol with Human Neuroglobin

2012 ◽  
Vol 27 ◽  
pp. 143-154 ◽  
Author(s):  
Lei Huang ◽  
Lianzhi Li ◽  
Haili Li ◽  
Chaohui Gao ◽  
Hui Cui ◽  
...  
Keyword(s):  
Fluorescence Spectra ◽  
Entropy Change ◽  
Cd Spectroscopy ◽  
Synchronous Fluorescence ◽  
Cd Spectra ◽  
Tyrosine Residues ◽  
Synchronous Fluorescence Spectra ◽  
Quenching Efficiency ◽  
Tryptophan Residues ◽  
Α Helix

The interaction between chloramphenicol (CHL) and neuroglobin (Ngb) has been investigated by using fluorescence, synchronous fluorescence, UV-Vis and circular dichroism (CD) spectroscopy. It has been found that CHL molecule can quench the intrinsic fluorescence of Ngb in a way of dynamic quenching mechanism, which was supported by UV-Vis spectral data. Their effective quenching constants (KSV) are2.2×104,2.6×104,and 3.1×104 L⋅mol−1at 298 K, 303 K, and 308 K, respectively. The enthalpy change (ΔH) and entropy change (ΔS) for this reaction are 26.42 kJ⋅mol−1and 171.7 J⋅K−1, respectively. It means that the hydrophobic interaction is the main intermolecular force of the interaction between CHL and Ngb. Synchronous fluorescence spectra showed that the microenvironment of tryptophan and tyrosine residues of Ngb has been changed slightly. The fluorescence quenching efficiency of CHL to tyrosine residues is a little bit more than that to tryptophan residues of Ngb. Furthermore, CD spectra indicated that CHL can induce the formation of α-helix of Ngb.

13C CP/MAS NMR Spectroscopic Characterization of Native Silk Fibers

2011 ◽  
Vol 175-176 ◽  
pp. 328-332 ◽  
Author(s):  
Wei Zhang ◽  
Jian Xin He ◽  
Yan Wang
Keyword(s):  
13C Nmr Spectroscopy ◽  
Spectroscopic Characterization ◽  
Random Coil ◽  
Silk Fibers ◽  
Significant Difference ◽  
Sheet Structure ◽  
Α Helix ◽  
Cp Mas Nmr ◽  
Β Sheet

Differences in secondary structure among Bombyx mori (B. mori) silk and two wild silks of Antheraea yamamai (A. yamamai) and Antheraea pernyi (A. pernyi) were investigated by CP/MAS 13C NMR Spectroscopy. The β-sheet structure was primary in three silk, and B. mori silk had the highest β-sheet structure. Although amino acid compositions are very similar for two wild silk, their secondary structures had significant difference. A. yamamai silk contained more α-helix structure, whereas more β-turn and random coil structures formed in A. pernyi silk. B. mori silk was mainly composed of anti-parallel β-sheet structure, however, the parallel β-sheet structure was advantage in the two wild silks, and A. yamamai silk contained more anti-parallel β-sheet conformation than A. pernyi silk.

Effects of Cosolvents and Macromolecular Crowding on the Phase Transitions and Temperature-Pressure Stability of Chiral and Racemic Poly-Lysine

2018 ◽  
Vol 232 (7-8) ◽  
pp. 1111-1125 ◽  
Author(s):  
Jim-Marcel Knop ◽  
Roland Winter
Keyword(s):  
Macromolecular Crowding ◽  
Helical Structure ◽  
Racemic Mixture ◽  
Sheet Structure ◽  
Different Types ◽  
Pressure Stability ◽  
Temperature And Pressure ◽  
Α Helix ◽  
Β Sheet ◽  
Volume Decrease

Abstract FTIR spectroscopy has been used to reveal the effects of different types of cosolvents (TMAO, urea) as well as macromolecular crowding (using the crowding agent Ficoll) on the temperature and pressure dependent structure of poly-L-lysine, poly-D-lysine and their racemic mixture. Compared to the effects of cosolvents on the unfolding transition of proteins, their effects on the α-helix to aggregated β-sheet transition of polylysine are quite small. High hydrostatic pressure has been found to favor the α-helical state over the aggregated β-sheet structure which is reflected in a volume decrease of ΔV=−32 mL mol−1, indicating that the packing mode is more efficient in the α-helical structure. Both, addition of urea and TMAO lead to a decrease in pressure stability of the aggregated β-sheet structure, which is accompanied by a three-fold decrease in ΔV, whereas the macromolecular crowder has little effect on the β-to-α transition. The more than 3 kbar higher β-to-α transition pressure of the racemic mixture compared with PLL confirms the drastic stabilization of β-sheet aggregates if the stereoisomers PLL and PDL are combined. Changes in hydration and packing of the polypeptide occurs upon interaction and fine packing of the polypeptide’s chains of opposed chirality, which are slightly modulated by the properties of cosolute and crowding, only. The underlying solvational and packing mechanisms observed here may be decisive factors responsible for the spontaneous protein aggregation in general and, as such, may shed additional light on the molecular basis of amyloid-associated diseases.

Scorpion toxin-potassium channel interaction law and its applications.

2020 ◽  
Vol 01 ◽  
Author(s):  
Zheng Zuo ◽  
Zongyun Chen ◽  
Zhijian Cao ◽  
Wenxin Li ◽  
Yingliang Wu
Keyword(s):  
Potassium Channel ◽  
Scorpion Toxin ◽  
Scorpion Toxins ◽  
Toxin Binding ◽  
Channel Interaction ◽  
Binding Interface ◽  
Α Helix ◽  
Interaction Law ◽  
Binding Interfaces ◽  
Β Sheet

: The scorpion toxins are the largest potassium channel-blocking peptide family. The understanding of toxin binding interfaces is usually restricted by two classical binding interfaces: one is the toxin α-helix motif, the other is the antiparallel β-sheet motif. In this review, such traditional knowledge was updated by another two different binding interfaces: one is BmKTX toxin using the turn motif between the α-helix and antiparallel β-sheet domains as the binding interface, the other is Ts toxin using turn motif between the β-sheet in the N-terminal and α-helix domains as the binding interface. Their interaction analysis indicated that the scarce negatively charged residues in the scorpion toxins played a critical role in orientating the toxin binding interface. In view of the toxin negatively charged amino acids as “binding interface regulator”, the law of scorpion toxin-potassium channel interaction was proposed, that is, the polymorphism of negatively charged residue distribution determines the diversity of toxin binding interfaces. Such law was used to develop scorpion toxin-potassium channel recognition control technique. According to this technique, three Kv1.3 channel-targeted peptides, using BmKTX as the template, were designed with the distinct binding interfaces from that of BmKTX through modulating the distribution of toxin negatively charged residues. In view of the potassium channel as the common targets of different animal toxins, the proposed law was also shown to helpfully orientate the binding interfaces of other animal toxins. Clearly, the toxin-potassium channel interaction law would strongly accelerate the research and development of different potassium channelblocking animal toxins in the future.

scholarly journals Nanostructure of bioactive glass affects bone cell attachment via protein restructuring upon adsorption

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ukrit Thamma ◽  
Tia J. Kowal ◽  
Matthias M. Falk ◽  
Himanshu Jain
Keyword(s):  
Bioactive Glass ◽  
Cell Response ◽  
Interfacial Layer ◽  
Cell Attachment ◽  
Bone Cell ◽  
Nano Structure ◽  
Rgd Sequence ◽  
Engineered Tissue ◽  
Α Helix ◽  
Β Sheet

AbstractThe nanostructure of engineered bioscaffolds has a profound impact on cell response, yet its understanding remains incomplete as cells interact with a highly complex interfacial layer rather than the material itself. For bioactive glass scaffolds, this layer comprises of silica gel, hydroxyapatite (HA)/carbonated hydroxyapatite (CHA), and absorbed proteins—all in varying micro/nano structure, composition, and concentration. Here, we examined the response of MC3T3-E1 pre-osteoblast cells to 30 mol% CaO–70 mol% SiO2 porous bioactive glass monoliths that differed only in nanopore size (6–44 nm) yet resulted in the formation of HA/CHA layers with significantly different microstructures. We report that cell response, as quantified by cell attachment and morphology, does not correlate with nanopore size, nor HA/CHO layer micro/nano morphology, or absorbed protein amount (bovine serum albumin, BSA), but with BSA’s secondary conformation as indicated by its β-sheet/α-helix ratio. Our results suggest that the β-sheet structure in BSA interacts electrostatically with the HA/CHA interfacial layer and activates the RGD sequence of absorbed adhesion proteins, such as fibronectin and vitronectin, thus significantly enhancing the attachment of cells. These findings provide new insight into the interaction of cells with the scaffolds’ interfacial layer, which is vital for the continued development of engineered tissue scaffolds.

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