scholarly journals Monitoring the Effects of Hemicellulase on the Different Proofing Stages of Wheat Aleurone-Rich Bread Dough and Bread Quality

Foods ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2427
Author(s):  
Boyu Tian ◽  
Chenxia Zhou ◽  
Dongxiao Li ◽  
Jiawei Pei ◽  
Ailiang Guo ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Disulfide Bonds ◽  
Hydrophobic Interactions ◽  
Hydrolytic Activity ◽  
Intermolecular Forces ◽  
Bread Quality ◽  
Ionic Bonds ◽  
Α Helix ◽  
Β Sheet

This study investigated the effects of a hemicellulase dosage (20, 40, and 60 mg kg−1 of flour) on the bread quality and rheological properties of wheat aleurone-rich flour. The results showed that hemicellulase could soften dough and improve extensibility. At the optimum hemicellulase dosage (40 mg kg−1 of flour), the bread specific volume increased by 40.91% and firmness of breadcrumb decreased by 104.57% compared to those of the control. Intermolecular forces indicated that the gluten network during the proofing was mainly strengthened via disulfide bonds, hydrophobic interactions, and hydrogen bonds but not through ionic bonds after hemicellulase addition. Fourier infrared spectroscopy indicated that the hydrolytic activity of hemicellulase catalyzed the transition from α-helix to β-sheet, which verified that viscoelasticity of gluten was enhanced at a dosage of 40 mg kg−1 of flour. These results suggested that hydrolyzation of hemicellulase contributed to the structural of gluten changes, thereby improving the quality of wheat aleurone-rich bread.

scholarly journals (De)stabilization of Alpha-Synuclein Fibrillary Aggregation by Charged and Uncharged Surfactants

2021 ◽  
Vol 22 (22) ◽  
pp. 12509
Author(s):  
Joana Angélica Loureiro ◽  
Stéphanie Andrade ◽  
Lies Goderis ◽  
Ruben Gomez-Gutierrez ◽  
Claudio Soto ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Hydrophobic Interactions ◽  
Neurodegenerative Disorder ◽  
Sodium Dodecyl ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Cetyltrimethylammonium Chloride ◽  
Α Helix ◽  
Β Sheet

Parkinson’s disease (PD) is the second most common neurodegenerative disorder. An important hallmark of PD involves the pathological aggregation of proteins in structures known as Lewy bodies. The major component of these proteinaceous inclusions is alpha (α)-synuclein. In different conditions, α-synuclein can assume conformations rich in either α-helix or β-sheets. The mechanisms of α-synuclein misfolding, aggregation, and fibrillation remain unknown, but it is thought that β-sheet conformation of α-synuclein is responsible for its associated toxic mechanisms. To gain fundamental insights into the process of α-synuclein misfolding and aggregation, the secondary structure of this protein in the presence of charged and non-charged surfactant solutions was characterized. The selected surfactants were (anionic) sodium dodecyl sulphate (SDS), (cationic) cetyltrimethylammonium chloride (CTAC), and (uncharged) octyl β-D-glucopyranoside (OG). The effect of surfactants in α-synuclein misfolding was assessed by ultra-structural analyses, in vitro aggregation assays, and secondary structure analyses. The α-synuclein aggregation in the presence of negatively charged SDS suggests that SDS-monomer complexes stimulate the aggregation process. A reduction in the electrostatic repulsion between N- and C-terminal and in the hydrophobic interactions between the NAC (non-amyloid beta component) region and the C-terminal seems to be important to undergo aggregation. Fourier transform infrared spectroscopy (FTIR) measurements show that β-sheet structures comprise the assembly of the fibrils.

A review of the interaction between anthocyanins and proteins

2020 ◽  
pp. 108201322096261
Author(s):  
Jia Li ◽  
Bixiang Wang ◽  
Yang He ◽  
Liankui Wen ◽  
Hailong Nan ◽  
...  
Keyword(s):  
Activation Energy ◽  
Structural Changes ◽  
Hydrophobic Interactions ◽  
Cd Spectroscopy ◽  
Hydrogen Bonding Interactions ◽  
The Stability ◽  
Α Helix ◽  
Proteins Interactions ◽  
Β Sheet ◽  
Different Sources

Anthocyanins have good physiological functions, but they are unstable. The interaction between anthocyanins and proteins can improve the stability, nutritional and functional properties of the complex. This paper reviews the structural changes of complex of anthocyanins interacting with proteins from different sources. By circular dichroism (CD) spectroscopy, it was found that the contents of α-helix (from 15.90%−42.40% to 17.60%−52.80%) or β-sheet (from 29.00%−50.00% to 29.40%−57.00%) of the anthocyanins–proteins complex increased. Fourier transform infrared spectroscopy showed that the regions of amide I (from 1627.87−1641.41 cm−1 to 1643.34−1651.02 cm−1) and amide II (from 1537.00−1540.25 cm−1 to 1539.00−1543.75 cm−1) of anthocyanins–proteins complex were shifted. Fluorescence spectroscopy showed that the fluorescence intensity of the complex decreased from 150−5100 to 40−3900 a.u. The thermodynamic analysis showed that there were hydrophobic interactions, electrostatic and hydrogen bonding interactions between anthocyanins and proteins. The kinetic analysis showed that the half-life and activation energy of the complex increased. The stability, antioxidant, digestion, absorption, and emulsification of the complex were improved. This provides a reference for the study and application of anthocyanins and proteins interactions.

scholarly journals Solution Structure of the Conserved Hypothetical Protein Rv2302 from Mycobacterium tuberculosis

2006 ◽  
Vol 188 (16) ◽  
pp. 5993-6001 ◽  
Author(s):  
Garry W. Buchko ◽  
Chang-Yub Kim ◽  
Thomas C. Terwilliger ◽  
Michael A. Kennedy
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Solution Structure ◽  
Hydrophobic Interactions ◽  
Hypothetical Protein ◽  
Cd Spectroscopy ◽  
Size Exclusion ◽  
Correlation Spectrum ◽  
Nuclear Overhauser ◽  
Α Helix ◽  
Β Sheet

ABSTRACT The Mycobacterium tuberculosis protein Rv2302 (80 residues; molecular mass of 8.6 kDa) has been characterized using nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy. While the biochemical function of Rv2302 is still unknown, recent microarray analyses show that Rv2302 is upregulated in response to starvation and overexpression of heat shock proteins and, consequently, may play a role in the biochemical processes associated with these events. Rv2302 is a monomer in solution as shown by size exclusion chromatography and NMR spectroscopy. CD spectroscopy suggests that Rv2302 partially unfolds upon heating and that this unfolding is reversible. Using NMR-based methods, the solution structure of Rv2302 was determined. The protein contains a five-strand, antiparallel β-sheet core with one C-terminal α-helix (A61 to A75) nestled against its side. Hydrophobic interactions between residues in the α-helix and β-strands 3 and 4 hold the α-helix near the β-sheet core. The electrostatic potential on the solvent-accessible surface is primarily negative with the exception of a positive arginine pocket composed of residues R18, R70, and R74. Steady-state {1H}-15N heteronuclear nuclear Overhauser effects indicate that the protein's core is rigid on the picosecond timescale. The absence of amide cross-peaks for residues G13 to H19 in the 1H-15N heteronuclear single quantum correlation spectrum suggests that this region, a loop between β-strands 1 and 2, undergoes motion on the millisecond to microsecond timescale. Dali searches using the structure closest to the average structure do not identify any high similarities to any other known protein structure, suggesting that the structure of Rv2302 may represent a novel protein fold.

Involvement of disulfide bonds and histidine 172 in a unique β-sheet to α-helix transition of α1-acid glycoprotein at the biomembrane interface

2006 ◽  
Vol 63 (3) ◽  
pp. 611-620 ◽  
Author(s):  
Koji Nishi ◽  
Yoshio Komine ◽  
Naoko Fukunaga ◽  
Toru Maruyama ◽  
Ayaka Suenaga ◽  
...  
Keyword(s):  
Disulfide Bonds ◽  
Acid Glycoprotein ◽  
Α Helix ◽  
Β Sheet

scholarly journals Effects of Selective Substitution of Cysteine Residues on the Conformational Properties of Chlorotoxin Explored by Molecular Dynamics Simulations

2019 ◽  
Vol 20 (6) ◽  
pp. 1261
Author(s):  
Andrew Gregory ◽  
Leah Voit-Ostricki ◽  
Sándor Lovas ◽  
Charles Watts
Keyword(s):  
Molecular Dynamics ◽  
Disulfide Bonds ◽  
Conformational Space ◽  
Amino Acid Peptide ◽  
Conformational Properties ◽  
Selective Substitution ◽  
Α Helix ◽  
Dynamics Simulations ◽  
High Degree ◽  
Β Sheet

Chlorotoxin (CTX) is a 36–amino acid peptide with eight Cys residues that forms four disulfide bonds. It has high affinity for the glioma-specific chloride channel and matrix metalloprotease-2. Structural and binding properties of CTX analogs with various Cys residue substitutions with l-α-aminobutyric acid (Abu) have been previously reported. Using 4.2 µs molecular dynamics, we compared the conformational and essential space sampling of CTX and analogs with selective substitution of the Cys residues and associated disulfide bonds with either Abu or Ser. The native and substituted peptides maintained a high degree of α-helix propensity from residues 8 through 21, with the exception of substitution of the Cys5–Cys28 residues with Ser and the Cys16–Cys33 residues with Abu. In agreement with previous circular dichroism spectropolarimetry results, the C-terminal β-sheet content varied less from residues 25 through 29 and 32 through 36 and was well conserved in most analogs. The Cys16–Cys33 and Cys20–Cys35 disulfide-bonded residues appear to be required to maintain the αβ motif of CTX. Selective substitution with the hydrophilic Ser, may mitigate the destabilizing effect of Cys16–Cys33 substitution through the formation of an inter residue H-bond from Ser16:OγH to Ser33:OγH bridged by a water molecule. All peptides shared considerable sampled conformational space, which explains the retained receptor binding of the non-native analogs.

Highly efficient extraction of large molecular-weight keratin from wool in a water/ethanol co-solvent

2019 ◽  
Vol 90 (9-10) ◽  
pp. 1084-1093 ◽  
Author(s):  
Jiahao He ◽  
Duo Xu ◽  
Junyu Li ◽  
Linfeng Li ◽  
Wenbin Li ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Disulfide Bonds ◽  
Hydrophobic Interactions ◽  
Random Coil ◽  
High Yield ◽  
Mixed System ◽  
Wool Fibers ◽  
Cysteine Hydrochloride ◽  
Α Helix

A large number of wool fiber by-products, short and coarse wool fibers are difficult to spin and are disposed of by the wool industry, creating a burden on the environment. In this study, L-cysteine hydrochloride and sodium sulfite were used as reducing agents to extract keratin from natural wool in an ethanol-water mixed system. The molecular weight of the extracted keratin is up to 130 kDa with a high yield of 67%. It has been proven that the reducing agent destroyed partial disulfide bonds, ethanol destroyed partial hydrogen bonds and hydrophobic interactions, and the α-helix chain was converted into a β-folded chain and random coil after extraction by instrumental analysis using a Fourier transform infrared spectrometer and X-ray diffraction. The recombination of small keratin molecules can be proven by the increase in protein particle size and molecular weight via a particle size analyzer and SDS-PAGE respectively.

Relation Of Heparin Binding And Conformation In PF4 AND LA-PF4 (βTG)

1981 ◽  
Author(s):  
John C Holt ◽  
Marek Kloczewiak ◽  
Daniel A Walz ◽  
Boguslaw Rucinski ◽  
Stefan Niewiarowski
Keyword(s):  
Amino Acid ◽  
Disulfide Bonds ◽  
Amino Acid Sequences ◽  
Platelet Factor 4 ◽  
Heparin Binding ◽  
Platelet Factor ◽  
Significant Difference ◽  
Lysine Residues ◽  
Α Helix ◽  
Β Sheet

Platelet factor 4 (PF4) and low affinity platelet factor 4 (LA-PF4) are platelet-specific secreted proteins that bind to heparin. β-thromboglobulin (βTG) appears to be derived from LA-PF4 by proteolysis of four NH2-terminal residues. PF4 and LA-PF4 (βTG) show 50% sequence homology including four cysteine residues and two pairs of lysine residues near the C00H-terminus which are believed to be responsible for heparin binding. Despite these similarities, the two proteins have markedly different affinities for heparin. We have sought a structural interpretation of this difference by predicting the conformations of 0TG, LA-PF4 and PF4. First, the proportion of residues in α-helical, β-sheet and unordered conformations was estimated from circular dichroism measurements. The results for PF4 and LA-PF4 were experimentally identical, namely 16% α-helix and 20% β-sheet. These values were then applied as experimental constraints in the prediction of the secondary structure of PF4 and LA-PF4 based on their amino acid sequences. This was done by a computer program which compared local amino acid sequence (each residue and 8 residues on either side) with the conformation of similar sequences in 25 proteins of known structure. With the further constraint of the two disulfide bonds in each molecule, models were constructed representing the overall folding of the polypeptide chains. The only significant difference between the two proteins was in the COOH-terminal region of the chains. The models suggest that the lower affinity of LA-PF4 (and βTG) for heparin may result from steric hindrance by the longer and more negatively charged COOH-terminal segments of these molecules compared with PF4.

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 Insight into the HIV-1 Vif SOCS-box–ElonginBC interaction

Open Biology ◽  
2013 ◽  
Vol 3 (11) ◽  
pp. 130100 ◽  
Author(s):  
Zhisheng Lu ◽  
Julien R. C. Bergeron ◽  
R. Andrew Atkinson ◽  
Torsten Schaller ◽  
Dennis A. Veselkov ◽  
...  
Keyword(s):  
Solution Structure ◽  
Hydrophobic Interactions ◽  
Dynamic Information ◽  
Ubiquitin Ligase Complex ◽  
Biophysical Studies ◽  
Viral Infectivity Factor ◽  
Β Sheet ◽  
Socs Box ◽  
Insight Into ◽  
Hiv 1

The HIV-1 viral infectivity factor (Vif) neutralizes cell-encoded antiviral APOBEC3 proteins by recruiting a cellular ElonginB (EloB)/ElonginC (EloC)/Cullin5-containing ubiquitin ligase complex, resulting in APOBEC3 ubiquitination and proteolysis. The suppressors-of-cytokine-signalling-like domain (SOCS-box) of HIV-1 Vif is essential for E3 ligase engagement, and contains a BC box as well as an unusual proline-rich motif. Here, we report the NMR solution structure of the Vif SOCS–ElonginBC (EloBC) complex. In contrast to SOCS-boxes described in other proteins, the HIV-1 Vif SOCS-box contains only one α-helical domain followed by a β-sheet fold. The SOCS-box of Vif binds primarily to EloC by hydrophobic interactions. The functionally essential proline-rich motif mediates a direct but weak interaction with residues 101–104 of EloB, inducing a conformational change from an unstructured state to a structured state. The structure of the complex and biophysical studies provide detailed insight into the function of Vif's proline-rich motif and reveal novel dynamic information on the Vif–EloBC interaction.

Quality of wheat breads enriched with flour from germinated amaranth seeds

2021 ◽  
pp. 108201322110165
Author(s):  
Luciano M Guardianelli ◽  
María V Salinas ◽  
María C Puppo
Keyword(s):  
Relaxation Time ◽  
Elastic Modulus ◽  
Wheat Flour ◽  
Specific Volume ◽  
Bread Quality ◽  
Maximum Volume ◽  
High Area ◽  
Amaranth Flour ◽  
Fermentation Parameters

Amaranth flour from germinated (GA) and non-germinated (A) seeds (0%-C, 5%, 15%, 25%) were mixed with wheat flour for breadmaking. Fermentation parameters of dough (time-tf, maximum volume-Vmax) were obtained. Specific volume (Vsp) of breads, crust color, texture and relaxation of crumb were analyzed. A high amount of germinated amaranth flour decreased Vmax and increased tf, obtaining breads with low Vsp and darkness crust. A firmed and chewy crumb, although with a more aerated structure (high area occupied by alveoli) was obtained. The GA25 bread presented the softer crumb. The elastic modulus-E1 of crumb increased and the relaxation time-T1 decreased with higher amounts of amaranth flour, suggesting the formation of a more structured crumb; mainly in the case of non-germinated amaranth flour. Wheat flour resisted the inclusion of 25% of germinated amaranth seeds (GA25) without substantial changes in bread quality.

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