The effect of aspirin-HSA complexation on the protein secondary structure

2000 ◽  
Vol 78 (2) ◽  
pp. 291-296 ◽  
Author(s):  
J F Neault ◽  
A Novetta-Delen ◽  
H Arakawa ◽  
H Malonga ◽  
H A Tajmir-Riahi
Keyword(s):  
Secondary Structure ◽  
Binding Constant ◽  
Structural Changes ◽  
Resolution Enhancement ◽  
Protein Secondary Structure ◽  
Binding Mode ◽  
Drug Binding ◽  
Drug Concentrations ◽  
Fitting Procedures ◽  
Α Helix

This study was designed to determine the secondary structure of human serum albumin (HSA) in the presence of aspirin in H2O and D2O solutions at physiological pH, using aspirin concentrations of 0.0001-5 mM with final protein concentration of 2% w/v. UV-vis spectra and Fourier transform infrared (FTIR) difference spectroscopy with its self-deconvolution, second derivative resolution enhancement, and curve-fitting procedures were applied to characterize the drug binding mode, the binding constant, and the protein secondary structure in the aspirin-HSA complexes. Spectroscopic evidence showed that no aspirin-protein interaction occurs at very low drug concentration (0.0001 mM), whereas at higher drug contents (0.001-0.1 mM) the aspirin anion binding (H-bonding) is mainly through the ε-amino NH3+ group with overall binding constant of K = 1.4 × 104 M-1. At high drug concentrations (1-5 mM), acetylation of Lys-199 was observed. Aspirin binding results in protein secondary structural changes from that of the α-helix 55% (free HSA) to 49%, β-sheet 22% (free HSA) to 31%, β-anti 12% (free HSA) to 4% and turn 11% (free HSA) to 16% in the aspirin-HSA complexes..Key words: aspirin, protein, drug, binding mode, binding constant secondary structure, FTIR spectroscopy.

Fourier-Transform Infrared Spectroscopic Investigation of the Secondary Structure of P2 Protein in Deuterium Oxide Solution

1991 ◽  
Vol 44 (11) ◽  
pp. 1523 ◽  
Author(s):  
BH Stuart ◽  
EF Mcfarlane
Keyword(s):  
Fourier Transform ◽  
Secondary Structure ◽  
Deuterium Oxide ◽  
Resolution Enhancement ◽  
Low Frequency ◽  
Fourier Transform Infrared ◽  
Crystallographic Study ◽  
Fitting Procedures ◽  
P2 Protein ◽  
Α Helix

Fourier transform infrared ( F.t.i.r .) spectroscopy has been used to investigate the secondary structure of bovine P2 protein in deuterium oxide (D2O) solution. The amide 1 region of the spectrum was analysed quantitatively by means of resolution enhancement and band-fitting procedures. The protein was found to consist mainly of β-structure (61%), with a small amount of α-helix (11%). A reason for the existence of an unusually intense low-frequency band assigned to β-structure is discussed. The F.t.i.r . results are compared with those from an X-ray crystallographic study and from circular dichroism and explanations are offered for discrepancies between the results from the different methods.

Secondary Structure Estimation of Proteins Using the Amide III Region of Fourier Transform Infrared Spectroscopy: Application to Analyze Calcium-Binding-Induced Structural Changes in Calsequestrin

1994 ◽  
Vol 48 (11) ◽  
pp. 1432-1441 ◽  
Author(s):  
Fen-Ni Fu ◽  
Daniel B. Deoliveira ◽  
William R. Trumble ◽  
Hemanta K. Sarkar ◽  
Bal Ram Singh
Keyword(s):  
Fourier Transform ◽  
Secondary Structure ◽  
Calcium Binding ◽  
Structural Changes ◽  
Spectroscopic Method ◽  
Spectral Feature ◽  
Protein Secondary Structure ◽  
Fourier Transform Infrared ◽  
Helical Structure ◽  
Α Helix

A Fourier transform infrared spectroscopic method has been developed to analyze protein secondary structure by employing the amide III spectral region (1350–1200 cm−1)· Benefits of using the amide III region have been shown to be substantial. The interference from the water vibration (∼1640 cm−1) in the amide I region can be avoided when one is using the amide III band; furthermore, the amide III region also presents a more characterized spectral feature which provides easily resolved and better defined bands for quantitative analysis. Estimates of secondary structure are accomplished with the use of Fourier self-deconvolution, second derivatization, and curve-fitting on original protein spectra. The secondary structure frequency windows (α-helix, 1328–1289 cm−1; unordered, 1288–1256 cm−1; and β-sheets, 1255–1224 cm−1) have been obtained, and estimates of secondary structural contents are consistent with X-ray crystallography data for model proteins and parallel results obtained with the use of the amide I region. We have further applied the analysis to the structural change of calsequestrin upon Ca2+ binding. Treatment of calsequestrin with 1 mM Ca2+ results in the formation of crystalline aggregates accompanied by a 10% increase in α-helical structure, which is consistent with previous results obtained by Raman spectroscopy. Thus the amide III region of protein IR spectra appears to be a valuable tool in estimating individual protein secondary structural contents.

RNase A – tRNA binding alters protein conformation

2007 ◽  
Vol 85 (3) ◽  
pp. 311-318 ◽  
Author(s):  
C.N. N’soukpoé-Kossi ◽  
C. Ragi ◽  
H.A. Tajmir-Riahi
Keyword(s):  
Binding Sites ◽  
Binding Constant ◽  
Structural Changes ◽  
Structural Information ◽  
Binding Mode ◽  
Rnase A ◽  
Random Coil ◽  
Pancreatic Ribonuclease A ◽  
Α Helix ◽  
Rna Interaction

Bovine pancreatic ribonuclease A (RNase A) catalyzes the cleavage of P-O5′ bonds in RNA on the 3′ side of pyrimidine to form cyclic 2′,5′-phosphates. Even though extensive structural information is available on RNase A complexes with mononucleotides and oligonucleotides, the interaction of RNase A with tRNA has not been fully investigated. We report the complexation of tRNA with RNase A in aqueous solution under physiological conditions, using a constant RNA concentration and various amounts of RNase A. Fourier transform infrared, UV-visible, and circular dichroism spectroscopic methods were used to determine the RNase binding mode, binding constant, sequence preference, and biopolymer secondary structural changes in the RNase–tRNA complexes. Spectroscopic results showed 2 major binding sites for RNase A on tRNA, with an overall binding constant of K = 4.0 × 105 (mol/L)–1. The 2 binding sites were located at the G-C base pairs and the backbone PO2 group. Protein–RNA interaction alters RNase secondary structure, with a major reduction in α helix and β sheets and an increase in the turn and random coil structures, while tRNA remains in the A conformation upon protein interaction. No tRNA digestion was observed upon RNase A complexation.

DNase I – DNA interaction alters DNA and protein conformations

2008 ◽  
Vol 86 (3) ◽  
pp. 244-250 ◽  
Author(s):  
C.N. N’soukpoé-Kossi ◽  
S. Diamantoglou ◽  
H.A. Tajmir-Riahi
Keyword(s):  
Binding Constant ◽  
Protein Secondary Structure ◽  
Binding Mode ◽  
Dna Interaction ◽  
Minor Groove ◽  
Dnase I ◽  
Protein Conformations ◽  
Physiological Conditions ◽  
Α Helix ◽  
The Right

Human DNase I is an endonuclease that catalyzes the hydrolysis of double-stranded DNA predominantly by a single-stranded nicking mechanism under physiological conditions in the presence of divalent Mg and Ca cations. It binds to the minor groove and the backbone phosphate group and has no contact with the major groove of the right-handed DNA duplex. The aim of this study was to examine the effects of DNase I – DNA complexation on DNA and protein conformations.We monitored the interaction of DNA with DNase I under physiological conditions in the absence of Mg2+, with a constant DNA concentration (12.5 mmol/L; phosphate) and various protein concentrations (10–250 µmol/L). We used Fourier transfrom infrared, UV-visible, and circular dichroism spectroscopic methods to determine the protein binding mode, binding constant, and effects of polynucleotide–enzyme interactions on both DNA and protein conformations. Structural analyses showed major DNase–PO2 binding and minor groove interaction, with an overall binding constant, K, of 5.7 × 105 ± 0.78 × 105 (mol/L)–1. We found that the DNase I – DNA interaction altered protein secondary structure, with a major reduction in α helix and an increase in β sheet and random structures, and that a partial B-to-A DNA conformational change occurred. No DNA digestion was observed upon protein–DNA complexation.

scholarly journals Structural and Technological Approach to Reveal the Role of the Lipid Phase in the Formation of Soy Emulsion Gels with Chia Oil

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 48
Author(s):  
Ana M. Herrero ◽  
Claudia Ruiz-Capillas
Keyword(s):  
Raman Spectroscopy ◽  
Structural Properties ◽  
Structural Changes ◽  
Protein Secondary Structure ◽  
Lipid Phase ◽  
Α Helix ◽  
Β Sheet ◽  
Shed Light ◽  
Chia Oil

Considerable attention has been paid to emulsion gels (EGs) in recent years due to their interesting applications in food. The aim of this work is to shed light on the role played by chia oil in the technological and structural properties of EGs made from soy protein isolates (SPI) and alginate. Two systems were studied: oil-free SPI gels (SPI/G) and the corresponding SPI EGs (SPI/EG) that contain chia oil. The proximate composition, technological properties (syneresis, pH, color and texture) and structural properties using Raman spectroscopy were determined for SPI/G and SPI/EG. No noticeable (p > 0.05) syneresis was observed in either sample. The pH values were similar (p > 0.05) for SPI/G and SPI/EG, but their texture and color differed significantly depending on the presence of chia oil. SPI/EG featured significantly lower redness and more lightness and yellowness and exhibited greater puncture and gel strengths than SPI/G. Raman spectroscopy revealed significant changes in the protein secondary structure, i.e., higher (p < 0.05) α-helix and lower (p < 0.05) β-sheet, turn and unordered structures, after the incorporation of chia oil to form the corresponding SPI/EG. Apparently, there is a correlation between these structural changes and the textural modifications observed.

Use of synchrotron-based FTIR microspectroscopy to determine protein secondary structures of raw and heat-treated brown and golden flaxseeds: A novel approach

2005 ◽  
Vol 85 (4) ◽  
pp. 437-448 ◽  
Author(s):  
P. Yu ◽  
J. J. McKinnon ◽  
H. W. Soita ◽  
C. R. Christensen ◽  
D. A. Christensen
Keyword(s):  
Secondary Structure ◽  
Matrix Protein ◽  
Protein Secondary Structure ◽  
Secondary Structures ◽  
Heat Processing ◽  
Lower Percentage ◽  
Protein Secondary Structures ◽  
Novel Approach ◽  
Α Helix ◽  
Β Sheet

The objectives of the study were to use synchrotron Fourier transform infrared microspectroscopy (S-FTIR) as a novel approach to: (1) reveal ultra-structural chemical features of protein secondary structures of flaxseed tissues affected by variety (golden and brown) and heat processing (raw and roasted), and (2) quantify protein secondary structures using Gaussian and Lorentzian methods of multi-component peak modeling. By using multi-component peak modeling at protein amide I region of 1700–1620 cm-1, the results showed that the golden flaxseed contained relatively higher percentage of α-helix (47.1 vs. 36.9%), lower percentage of β-sheet (37.2 vs. 46.3%) and higher (P < 0.05) ratio of α-helix to β-sheet than the brown flaxseed (1.3 vs. 0.8). The roasting reduced (P < 0.05) percentage of α-helix (from 47.1 to 36.1%), increased percentage of β-sheet (from 37.2 to 49.8%) and reduced α-helix to β-sheet ratio (1.3 to 0.7) of the golden flaxseed tissues. However, the roasting did not affect percentage and ratio of α-helix and β-sheet in the brown flaxseed tissue. No significant differences were found in quantification of protein secondary structures between Gaussian and Lorentzian methods. These results demonstrate the potential of highly spatially resolved S-FTIR to localize relatively pure protein in the tissue and reveal protein secondary structures at a cellular level. The results indicated relative differences in protein secondary structures between flaxseed varieties and differences in sensitivities of protein secondary structure to the heat processing. Further study is needed to understand the relationship between protein secondary structure and protein digestion and utilization of flaxseed and to investigate whether the changes in the relative amounts of protein secondary structures are primarily responsible for differences in protein availability. Key words: Synchrotron, FTIR microspectrosopy, flaxseeds, intrinsic structural matrix, protein secondary structures, protein nutritive value

Interaction of RNase A with VO3-and VO2+Ions. Metal Ion Binding Mode and Protein Secondary Structure

1999 ◽  
Vol 17 (3) ◽  
pp. 473-480 ◽  
Author(s):  
M. Purcell ◽  
A. Novetta-Delen ◽  
H. Arakawa ◽  
H. Malonga ◽  
H. A. Tajmir-Riahi
Keyword(s):  
Secondary Structure ◽  
Metal Ion ◽  
Protein Secondary Structure ◽  
Binding Mode ◽  
Rnase A ◽  
Ion Binding ◽  
Metal Ion Binding

scholarly journals Structural Changes of β-Casein Induced by Temperature and pH Analysed by Nuclear Magnetic Resonance, Fourier-Transform Infrared Spectroscopy, and Chemometrics

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7650
Author(s):  
Tatijana Markoska ◽  
Davor Daniloski ◽  
Todor Vasiljevic ◽  
Thom Huppertz
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Magnetic Resonance ◽  
Secondary Structure ◽  
Structural Changes ◽  
Hydrophobic Interactions ◽  
Fourier Transform Infrared ◽  
Helical Structures ◽  
Random Coils ◽  
Α Helix

This study investigated structural changes in β-casein as a function of temperature (4 and 20 °C) and pH (5.9 and 7.0). For this purpose, nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy were used, in conjunction with chemometric analysis. Both temperature and pH had strongly affected the secondary structure of β-casein, with most affected regions involving random coils and α-helical structures. The α-helical structures showed great pH sensitivity by decreasing at 20 °C and diminishing completely at 4 °C when pH was increased from 5.9 to 7.0. The decrease in α-helix was likely related to the greater presence of random coils at pH 7.0, which was not observed at pH 5.9 at either temperature. The changes in secondary structure components were linked to decreased hydrophobic interactions at lower temperature and increasing pH. The most prominent change of the α-helix took place when the pH was adjusted to 7.0 and the temperature set at 4 °C, which confirms the disruption of the hydrogen bonds and weakening of hydrophobic interactions in the system. The findings can assist in establishing the structural behaviour of the β-casein under conditions that apply as important for solubility and production of β-casein.

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