scholarly journals FTIR Spectroscopy Study of the Secondary Structure Changes in Human Serum Albumin and Trypsin under Neutral Salts

Biomolecules ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 606 ◽  
Author(s):  
Dmitrii Usoltsev ◽  
Vera Sitnikova ◽  
Andrey Kajava ◽  
Mayya Uspenskaya

The effect of neutral salts on protein conformation was first analyzed by Hofmeister in 1888, however, even today this phenomenon is not completely understood. To clarify this effect, we studied changes in the secondary structure of two proteins: human serum albumin with predominantly α-helical structure and porcine pancreas β-trypsin with the typical β-structural arrangement in aqueous solutions of neutral salts (KSCN, KCl, (NH4)2SO4). The changes in the secondary structure were studied at 23 °C and 80 °C by using the second derivative deconvolution method of the IR spectra. Our results demonstrated that the ability of the salts to stabilize/destabilize these two proteins correlates with the Hofmeister series of ions. At the same time, some exceptions were also observed. The destabilization of the native structures of both α-helical albumin and β-structural trypsin upon interaction with neutral salts leads to the formation of intermolecular β-sheets typical for amyloid fibrils or amorphous aggregates. Thus, our quantitative FTIR-spectroscopy analysis allowed us to further clarify the mechanisms and complexity of the neutral salt actions on protein structures which may lead to strategies preventing unwelcome misfolding of proteins.

Biomolecules ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 359 ◽  
Author(s):  
Usoltsev ◽  
Sitnikova ◽  
Kajava ◽  
Uspenskaya

Human serum albumin (HSA) is the most abundant protein in blood plasma. HSA is involved in the transport of hormones, fatty acids, and some other compounds, maintenance of blood pH, osmotic pressure, and many other functions. Although this protein is well studied, data about its conformational changes upon different denaturation factors are fragmentary and sometimes contradictory. This is especially true for FTIR spectroscopy data interpretation. Here, the effect of various denaturing agents on the structural state of HSA by using FTIR spectroscopy in the aqueous solutions was systematically studied. Our data suggest that the second derivative deconvolution method provides the most consistent interpretation of the obtained IR spectra. The secondary structure changes of HSA were studied depending on the concentration of the denaturing agent during acid, alkaline, and thermal denaturation. In general, the denaturation of HSA in different conditions is accompanied by a decrease in α-helical conformation and an increase in random coil conformation and the intermolecular β-strands. Meantime, some variation in the conformational changes depending on the type of the denaturation agent were also observed. The increase of β-structural conformation suggests that HSA may form amyloid-like aggregates upon the denaturation.


2005 ◽  
Vol 743 (1-3) ◽  
pp. 79-84 ◽  
Author(s):  
Ying Li ◽  
WenYing He ◽  
Jianniao Tian ◽  
Jianghong Tang ◽  
Zhide Hu ◽  
...  

2019 ◽  
Vol 278 ◽  
pp. 553-567 ◽  
Author(s):  
Tajalli Ilm Chandel ◽  
Aiman Masroor ◽  
Mohammad Khursheed Siddiqi ◽  
Ibrar Ahmad Siddique ◽  
Ishrat Jahan ◽  
...  

1992 ◽  
Vol 85 (1-3) ◽  
pp. 39-44 ◽  
Author(s):  
Naoko Ohta ◽  
Toshihisa Yotsuyanagi ◽  
Danni Chen ◽  
Rikako Ono ◽  
Shigekazu Ito ◽  
...  

2018 ◽  
Vol 62 (2) ◽  
pp. 85-91 ◽  
Author(s):  
J. Staničová ◽  
K. Želonková ◽  
V. Verebová ◽  
B. Holečková ◽  
J. Dianovský

Abstract The interactions between the fungicide tebuconazole and human serum albumin were investigated using fluorescence and circular dichroism spectroscopies. The experimental results showed that the fluorescence quenching of the protein by the tebuconazole molecule was a result of the formation of a ligand-protein complex with a binding constant of 8.51×103 l.mol−1 and the number of binding sites in the macromolecule was close to 1. These findings demonstrated the fact that although the binding affinity of tebuconazole to the protein may be slight, it was very similar to other triazole fungicides. In addition, tebuconazole stabilized the α-helical secondary structure of the human serum albumin due to the increase of the α-content in the protein macromolecule.


1979 ◽  
Vol 44 (5) ◽  
pp. 1657-1670 ◽  
Author(s):  
Ladislav Morávek ◽  
Mohamed Ali Saber ◽  
Bedřich Meloun

Human serum albumin was nitrated by an excess of tetranitromethane at pH 8.0. As shown by amino acid analysis, of the 18 tyrosine residues present in albumin about 7-7.5 residues remain unaltered, 9 residues are converted into 3-nitrotyrosine, and 1.2 residue into 3,5-dinitrotyrosine. The nitrated albumin was digested with cyanogen bromide to three fragments which comprise the whole original molecule. The individual fragments were converted into their S-sulfo derivatives and the latter digested with chymotrypsin or stepwise with trypsin and thermolysin. The yellow, nitrotyrosine-containing peptides were isolated from the digest and the positions of nitrated tyrosine residues in albumin thus located. Residues No 30, 148, 150, 161, 334, 341, 401, and 411 were identified as strongly nitrated and residues No 84, 138, 452, and 497 as medium nitrated. Residues No 140, 263, 319, 332, 353, and 367 either react weakly or were not found in nitrated form. Residue No 411 and partly also 161 were converted into 3,5-dinitrotyrosine. The accessibility of the individual tyrosine residues to the nitrating agent is discussed with respect to their positions in disulfide loops and hypothetic parts of the secondary structure of albumin.


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