scholarly journals The Effect of Luteolin and Luteoloside on the Secondary Structure of Lysozyme

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yu Wu ◽  
Lijian Cui ◽  
Lingling Qu ◽  
Rong Wang ◽  
Ning Chen ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Biological Activity ◽  
Secondary Structure ◽  
Raman Spectra ◽  
Active Site ◽  
Lysozyme Activity ◽  
Relative Content ◽  
Significant Difference ◽  
Α Helix

The changes of lysozyme conformation in the absence and presence of luteolin and luteoloside were investigated by spectral analysis including fluorescence, UV, CD, Raman, and ATR-FTIR, and the biological activity of lysozyme was investigated by lysozyme assay kit. The results showed that the microenvironment hydrophobicity of lysozyme increased and peptide extension decreased with the addition of luteolin or luteoloside. The α-helix of lysozyme might be influenced by luteolin or luteoloside, and its relative content had a significant difference after adding luteolin or luteoloside by the ATR-FTIR method, which was reconfirmed by CD and Raman spectra. The lysozyme activity changed obviously after adding luteolin or luteoloside. All of the conclusions above indicated the active site of lysozyme in the α-helix might be influenced by luteolin and luteoloside.

scholarly journals Secondary Structure of Bovine Albumin as Studied by Polarization-Sensitive Multiplex CARS Spectroscopy

1996 ◽  
Vol 50 (1) ◽  
pp. 78-85 ◽  
Author(s):  
Artemy Voroshilov ◽  
Cees Otto ◽  
Jan Greve
Keyword(s):  
Secondary Structure ◽  
Raman Spectra ◽  
Random Coil ◽  
Background Suppression ◽  
Good Correspondence ◽  
Bovine Albumin ◽  
Suppression Technique ◽  
Polarized Raman ◽  
Α Helix ◽  
Anti Stokes

The first application of polarization-sensitive multiplex coherent anti-Stokes Raman spectroscopy (MCARS) in the absence of resonance enhancement to the resolution of the secondary structure of a protein in solution is reported. Polarization MCARS spectra of bovine albumin in D2O were obtained in the range 1370 to 1730 cm−1 with the aid of the background suppression technique. The spectra were fitted simultaneously with a single set of parameters (band positions, bandwidths, amplitudes, and depolarization ratios). Polarized Raman spectra simulated with these parameters revealed a good correspondence with the spontaneous Raman spectra measured. The broad amide I′ band was decomposed assuming the three major secondary conformations of protein, of which the contribution of β-sheet structure was found to be negligible. Relative weights of α-helix and random coil conformations agree well with the estimates obtained with Raman and circular dichroism (CD) spectroscopies.

scholarly journals Effects of Temperature on the FT NIR Raman Spectra of Fish Skin Collagen

2021 ◽  
Vol 11 (18) ◽  
pp. 8358
Author(s):  
Maria Połomska ◽  
Leszek Kubisz ◽  
Jacek Wolak ◽  
Dorota Hojan-Jezierska
Keyword(s):  
Molecular Structure ◽  
Raman Spectroscopy ◽  
Secondary Structure ◽  
Raman Spectra ◽  
Molecular Organization ◽  
Fish Skin ◽  
Temperature Range ◽  
Skin Collagen ◽  
Α Helix ◽  
Fish Skin Collagen

The development of regenerative medicine turns attention toward native collagen as a biocompatible material. Particularly interesting is fish skin collagen, which is relatively easy to extract comparing mammalian tissues and free of some pathogens that are dangerous to humans. The paper presents results of IR Raman spectroscopy studies of silver carp (Hypophthalmichthys molitrix) skin collagen. As collagen properties result from its structure and conformation, both sensitive to temperature, FT NIR Raman spectroscopy is an excellent tool to characterize the molecular structure of fish skin collagen, particularly in temperature range typical for the manufacturing processes of biomedical products. Therefore, the Raman spectra were recorded in a temperature range of 300 to 403 K. The analysis of Raman spectra of prepared collagen films, particularly in the range of the bands related to amide I and amide III entities, showed a high content of α-helix and α-helix type molecular organization in fish skin collagen. Additionally, the secondary structure of the studied fish skin collagen is stable up to ~358 K. Heating to 403 K leads to irreversible changes in the molecular structure of fish skin collagen. It was found that the Raman spectrum of fish skin collagen preheated in this manner becomes similar to the spectrum of the collagen obtained from bovine Achilles tendon, whose secondary structure does not change up to 403 K.

scholarly journals Effect of High Blood Cortisol Concentration on the Spectroscopically Determined Secondary Structure of Proteins and Lipid Balance on the Example of Elite Women Volleyball Players

2021 ◽  
Author(s):  
Joanna Depciuch ◽  
Wojciech Czarny ◽  
Wojciech Szuszkiewicz ◽  
Adam Reich ◽  
Bartosz Klebowski ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Raman Spectra ◽  
Pearson Correlation ◽  
Cortisol Concentration ◽  
Transmission Spectra ◽  
Volleyball Players ◽  
Pearson Correlation Test ◽  
Α Helix ◽  
Secondary Structure Of Proteins ◽  
Structure Of Proteins

Abstract Cortisol is a stress hormone plays a crucial role in the balance between phospholipids and lipids level. In consequence, it affects the secondary structure of proteins. Currently cortisol concentration in plasma is determined by biochemical analysis. A new, optical method to estimate stress level is proposed in this work. Infrared and Raman spectroscopies were used to determine quantitative and qualitative changes in the lipids and proteins fraction in function of cortisol concentration in 49 samples of plasma collected from volleyball players at various stages of preparation for the competition. With the cortisol level increase, a decrease of structures related to PO2- phospholipids groups and amides III, II and I bonds was noticed in the transmission spectra. Changes in the secondary structure of protein were indicated as a frequency shift of α-helix and β-sheet vibrations observed in Raman spectra and second derivative of transmission spectra. Pearson correlation test presented positive correlations between phospholipids and proteins level and between cortisol concentration and phospholipids in transmittance spectra. Negative correlations between cortisol concentration and proteins and phospholipids level was observed in the Raman spectra. Both optical techniques are considered to become effective tools for estimating the concentration of cortisol in the plasma.

scholarly journals D-Amino Acid-Containing Lipopeptides Derived from the Lead Peptide BP100 with Activity against Plant Pathogens

2021 ◽  
Vol 22 (12) ◽  
pp. 6631
Author(s):  
Àngel Oliveras ◽  
Luís Moll ◽  
Gerard Riesco-Llach ◽  
Arnau Tolosa-Canudas ◽  
Sergio Gil-Caballero ◽  
...  
Keyword(s):  
Biological Activity ◽  
Amino Acid ◽  
Secondary Structure ◽  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Biological Profile ◽  
High Antimicrobial Activity ◽  
Hydrophobic Chain ◽  
Bacteria And Fungi ◽  
Α Helix

From a previous collection of lipopeptides derived from BP100, we selected 18 sequences in order to improve their biological profile. In particular, analogues containing a D-amino acid at position 4 were designed, prepared, and tested against plant pathogenic bacteria and fungi. The biological activity of these sequences was compared with that of the corresponding parent lipopeptides with all L-amino acids. In addition, the influence of the length of the hydrophobic chain on the biological activity was evaluated. Interestingly, the incorporation of a D-amino acid into lipopeptides bearing a butanoyl or a hexanoyl chain led to less hemolytic sequences and, in general, that were as active or more active than the corresponding all L-lipopeptides. The best lipopeptides were BP475 and BP485, both incorporating a D-Phe at position 4 and a butanoyl group, with MIC values between 0.8 and 6.2 µM, low hemolysis (0 and 24% at 250 µM, respectively), and low phytotoxicity. Characterization by NMR of the secondary structure of BP475 revealed that the D-Phe at position 4 disrupts the α-helix and that residues 6 to 10 are able to fold in an α-helix. This secondary structure would be responsible for the high antimicrobial activity and low hemolysis of this lipopeptide.

scholarly journals Solution NMR structures of oxidized and reducedEhrlichia chaffeensisthioredoxin: NMR-invisible structure owing to backbone dynamics

2018 ◽  
Vol 74 (1) ◽  
pp. 46-56
Author(s):  
Garry W. Buchko ◽  
Stephen N. Hewitt ◽  
Wesley C. Van Voorhis ◽  
Peter J. Myler
Keyword(s):  
Active Site ◽  
Solution Structure ◽  
Helical Structure ◽  
Backbone Dynamics ◽  
Redox States ◽  
Nmr Structures ◽  
Significant Difference ◽  
Cd Studies ◽  
Α Helix ◽  
Nmr Solution Structures

Thioredoxins are small ubiquitous proteins that participate in a diverse variety of redox reactionsviathe reversible oxidation of two cysteine thiol groups in a structurally conserved active site. Here, the NMR solution structures of a reduced and oxidized thioredoxin fromEhrlichia chaffeensis(Ec-Trx, ECH_0218), the etiological agent responsible for human monocytic ehrlichiosis, are described. The overall topology of the calculated structures is similar in both redox states and is similar to those of other thioredoxins: a five-stranded, mixed β-sheet (β1–β3–β2–β4–β5) surrounded by four α-helices. Unlike other thioredoxins studied by NMR in both redox states, the1H–15N HSQC spectrum of reducedEc-Trx was missing eight additional amide cross peaks relative to the spectrum of oxidizedEc-Trx. These missing amides correspond to residues Cys35–Glu39 in the active-site-containing helix (α2) and Ser72–Ile75 in a loop near the active site, and suggest a change in backbone dynamics on the millisecond-to-microsecond timescale associated with the breakage of an intramolecular Cys32–Cys35 disulfide bond in a thioredoxin. A consequence of the missing amide resonances is the absence of observable or unambiguous NOEs to provide the distance restraints necessary to define the N-terminal end of the α-helix containing the CPGC active site in the reduced state. This region adopts a well defined α-helical structure in other reported reduced thioredoxin structures, is mostly helical in oxidizedEc-Trx and CD studies ofEc-Trx in both redox states suggests there is no significant difference in the secondary structure of the protein. The NMR solution structure of reducedEc-Trx illustrates that the absence of canonical structure in a region of a protein may be owing to unfavorable dynamics prohibiting NOE observations or unambiguous NOE assignments.

Effect of Temperature and pH on the Secondary Structure and Denaturation Process of Jumbo Squid Hepatopancreas Cathepsin D.

2019 ◽  
Vol 26 (7) ◽  
pp. 532-541 ◽  
Author(s):  
Cadena-Cadena Francisco ◽  
Cárdenas-López José Luis ◽  
Ezquerra-Brauer Josafat Marina ◽  
Cinco-Moroyoqui Francisco Javier ◽  
López-Zavala Alonso Alexis ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Secondary Structure ◽  
Cathepsin D ◽  
Thermal Denaturation ◽  
Protein Denaturation ◽  
Marine Organisms ◽  
Effect Of Temperature ◽  
Jumbo Squid ◽  
Α Helix ◽  
Circular Dichroïsm

Background: Cathepsin D is a lysosomal enzyme that is found in all organisms acting in protein turnover, in humans it is present in some types of carcinomas, and it has a high activity in Parkinson's disease and a low activity in Alzheimer disease. In marine organisms, most of the research has been limited to corroborate the presence of this enzyme. It is known that cathepsin D of some marine organisms has a low thermostability and that it has the ability to have activity at very acidic pH. Cathepsin D of the Jumbo squid (Dosidicus gigas) hepatopancreas was purified and partially characterized. The secondary structure of these enzymes is highly conserved so the role of temperature and pH in the secondary structure and in protein denaturation is of great importance in the study of enzymes. The secondary structure of cathepsin D from jumbo squid hepatopancreas was determined by means of circular dichroism spectroscopy. Objective: In this article, our purpose was to determine the secondary structure of the enzyme and how it is affected by subjecting it to different temperature and pH conditions. Methods: Circular dichroism technique was used to measure the modifications of the secondary structure of cathepsin D when subjected to different treatments. The methodology consisted in dissecting the hepatopancreas of squid and freeze drying it. Then a crude extract was prepared by mixing 1: 1 hepatopancreas with assay buffer, the purification was in two steps; the first step consisted of using an ultrafiltration membrane with a molecular cut of 50 kDa, and the second step, a pepstatin agarose resin was used to purification the enzyme. Once the enzyme was purified, the purity was corroborated with SDS PAGE electrophoresis, isoelectric point and zymogram. Circular dichroism is carried out by placing the sample with a concentration of 0.125 mg / mL in a 3 mL quartz cell. The results were obtained in mdeg (millidegrees) and transformed to mean ellipticity per residue, using 111 g/mol molecular weight/residue as average. Secondary-structure estimation from the far-UV CD spectra was calculated using K2D Dichroweb software. Results: It was found that α helix decreases at temperatures above 50 °C and above pH 4. Heating the enzyme above 70°C maintains a low percentage of α helix and increases β sheet. Far-UV CD measurements of cathepsin D showed irreversible thermal denaturation. The process was strongly dependent on the heating rate, accompanied by a process of oligomerization of the protein that appears when the sample is heated, and maintained a certain time at this temperature. An amount typically between 3 and 4% α helix of their secondary structure remains unchanged. It is consistent with an unfolding process kinetically controlled due to the presence of an irreversible reaction. The secondary structure depends on pH, and a pH above 4 causes α helix structures to be modified. Conclusion: In conclusion, cathepsin D from jumbo squid hepatopancreas showed retaining up to 4% α helix at 80°C. The thermal denaturation of cathepsin D at pH 3.5 is under kinetic control and follows an irreversible model.

The melanocyte stimulating activity of N-nitroso-2-chloroethyl-carbamoyl derivatives of α-melanotropin fragments

1988 ◽  
Vol 53 (11) ◽  
pp. 2574-2582 ◽  
Author(s):  
Hedvig Medzihradszky-Schweiger ◽  
Helga Süli-Vargha ◽  
József Bódi ◽  
Kálmán Medzihradszky
Keyword(s):  
Biological Activity ◽  
Active Site ◽  
Frog Skin ◽  
Terminal Sequence ◽  
Subsequent Reaction ◽  
Affinity Labels ◽  
Derivatives Of

A number of N-nitroso-2-chloroethyl-carbamoyl (Q(NO)) derivatives of α-melanotropin fragments have been synthesized and their effect on the frog skin melanocytes studied. Peptides substituted in this way possess the biological activity of the parent compounds, indicating that they preserved their receptor recognizing ability. These compounds can therefore serve as affinity labels. Some of these derivatives, related to the C-terminal sequence of α-melanotropin show prolonged darkening reaction, which does not influence the subsequent reaction of melanocytes with α-melanotropin. The Q(NO)-derivative of a fragment derived from the classical active site of the hormone shows, however, inhibition of the effect of α-melanotropin. It can be concluded that the latter peptide acts through the melanotropin receptor, while others, related to the C-terminal sequence of the hormone through another mechanism.

scholarly journals Characterization of porcine osteonectin extracted from foetal calvariae

1988 ◽  
Vol 253 (1) ◽  
pp. 139-151 ◽  
Author(s):  
C Domenicucci ◽  
H A Goldberg ◽  
T Hofmann ◽  
D Isenman ◽  
S Wasi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Secondary Structure ◽  
Type I Collagen ◽  
Culture Shock ◽  
Gel Filtration ◽  
Alpha Helix ◽  
Type I ◽  
Homologous Proteins ◽  
Compact Structure ◽  
Significant Difference

Osteonectin, extracted from foetal porcine calvariae with 0.5 M-EDTA, was purified to homogeneity by using gel filtration and polyanion anion-exchange fast protein liquid chromatography under dissociative conditions without the need of reducing agents. The purified protein migrated with an Mr of 40,300 on SDS/polyacrylamide gels and was similar to bovine osteonectin in both amino acid composition and in its ability to bind to hydroxyapatite in the presence of 4 M-guanidinium hydrochloride (GdmCl). However, unlike the bovine protein, porcine osteonectin did not bind selectively to hydroxyapatite when EDTA tissue extracts were used. In addition, purified porcine osteonectin did not show any apparent affinity for either native or denatured type I collagen, but did bind to serum albumin. Primary sequence analysis revealed an N-terminal alanine residue, with approximately one-half of the subsequent 35 residues identified as small hydrophobic amino acids and one-quarter as acidic amino acids. The only significant difference between the N-terminal sequences of the bovine and porcine proteins was the deletion of the tripeptide Val-Ala-Glu in porcine osteonectin. In contrast with bovine osteonectin, far-u.v.c.d. of porcine osteonectin revealed considerable secondary structure, of which 27% was alpha-helix and 39% was beta-sheet. Cleavage of the molecule with CNBr under non-reducing conditions generated five fragments, of which two major fragments (Mr 27,900 and 12,400) stained blue with Stains All, a reagent that stains sialic-acid-rich proteins/phosphate-containing proteins and/or Ca2+-binding proteins blue while staining other proteins pink. The 12,400-Mr fragment bound 45Ca2+ selectively, indicating a Ca2+-binding site in this part of the molecule. The 27,900-Mr fragment did not bind Ca2+, and since biosynthetic studies with 32PO4(3-) did not show phosphorylation of porcine osteonectin, this fragment is likely to be highly acidic. The incomplete cleavage of the molecule with CNBr and the ability of the molecule to regain its secondary structure after exposure to 7 M-urea are features consistent with the molecule having a compact structure that is stabilized by numerous disulphide bridges. The chemical and binding properties of porcine osteonectin are closely similar to the recently described ‘culture shock’, SPARC and BM-40 proteins, indicating that these are homologous proteins.

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