Hydrophobic Core and Surface Charges of Human β2-Microglobulin Probed by CD Measurements

1992 ◽  
Vol 57 (5) ◽  
pp. 1143-1148
Author(s):  
Milanka Vučić ◽  
Paul Bray ◽  
Mire Zloh ◽  
Dušan Vučelić
Keyword(s):  
Sodium Perchlorate ◽  
Close Packing ◽  
Hydrophobic Core ◽  
Surface Charges ◽  
Ph Values ◽  
Nacl Concentration ◽  
Perchlorate Concentration ◽  
Enthalpy And Entropy ◽  
Β Sheets ◽  
Β Sheet

The roles of hydrophobic bonding and charge electrostatics in the stabilization of human β2-microglobulin have been probed by variations in solution conditions and monitored by circular dichroism in the near and far UV regions. Sodium perchlorate initially gives a decrease in intensity of the positive 234 nm peak in the near UV followed by a shift of this peak to negative ellipticity at high perchlorate concentration. These 234 nm changes indicate a new environment for a tyrosyl chromophore(s). A conformational rearrangement of the β-sheet sandwich must occur since all six tyrosines of human β2-microglobulin are located in the two β-sheets of this sandwich. A slight decrease in intensity for the 200 nm positive peak in the far UV indicates a less close packing of the β-sheets at high perchlorate. In other experiments, enthalpy and entropy values have been calculated from thermal unfolding studies at 50 and 180 mM NaCl for pH values 6.0 and 8.0. Larger enthalpy values are obtained at higher NaCl concentration consistent with salt shielding of predominantly unfavorable charge interactions. These enthalpy differences are relatively large suggesting that charge electrostatics are energetically significant in stabilization of human β2-microglobulin.

scholarly journals The Status of Edge Strands in Ferredoxin-Like Fold

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1032
Author(s):  
Mateusz Banach ◽  
Piotr Fabian ◽  
Katarzyna Stapor ◽  
Leszek Konieczny ◽  
Magdalena Ptak-Kaczor ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Hydrophobic Core ◽  
Current Analysis ◽  
Professional Literature ◽  
The Status ◽  
The Subject ◽  
Β Sheets ◽  
Β Sheet

There is an opinion in professional literature that edge-strands in β-sheet are critical to the processes of amyloid transformation. Propagation of fibrillar forms mainly takes place on the basis of β-sheet type interactions. In many proteins, the edge strands represent only a partially matched form to the β-sheet. Therefore, the edge-strand takes slightly distorted forms. The assessment of the level of arrangement can be carried out based on studying the secondary structure as well as the structure of the hydrophobic core. For this purpose, a fuzzy oil drop model was used to determine the contribution of each fragment with a specific secondary structure to the construction of the system being the effect of a certain synergy, which results in the construction of a hydrophobic core. Studying the participation of β-sheets edge fragments in the hydrophobic core construction is the subject of the current analysis. Statuses of these edge fragments in β-sheets in ferredoxin-like folds are treated as factors that disturb the symmetry of the system.

scholarly journals Factors involved in the stability of isolated β-sheets: Turn sequence, β-sheet twisting, and hydrophobic surface burial

2004 ◽  
Vol 13 (4) ◽  
pp. 1134-1147 ◽  
Author(s):  
Clara M. Santiveri ◽  
Jorge Santoro ◽  
Manuel Rico ◽  
M. Angeles Jiménez
Keyword(s):  
Hydrophobic Surface ◽  
Β Sheets ◽  
The Stability ◽  
Β Sheet

scholarly journals Porous peptide frameworks generated by stacking non-self-complementary β-sheets

2014 ◽  
Vol 70 (a1) ◽  
pp. C562-C562
Author(s):  
Dmitriy Soldatov ◽  
Abdolreza Yazdani ◽  
Julia Crewson ◽  
Travis Fillion ◽  
Aaron Smith ◽  
...  
Keyword(s):  
Interlayer Space ◽  
Specific Property ◽  
Close Packing ◽  
Bioactive Molecules ◽  
Structural Motif ◽  
Supramolecular Polymers ◽  
Amino Acid Residues ◽  
Crystalline Materials ◽  
Wide Range ◽  
Β Sheet

"One of major approaches in the design of cavity space in the solids utilizes non-self-complementary molecules[1]. The irregular shape of the molecules and/or specific directionality of potential H-bonds prevent close packing of the molecules and yields various architectures hosting a second component, from inclusion compounds and co-crystals to complex non-crystalline patterns in biology. The strategy of non-self-complementary molecules has been extended in our studies to 2D supramolecular polymers based on short peptides[2]. The formation of the peptide layer with a desired overall geometry is controlled by strong, charge-assisted H-bonds (arrows in the Figure) in a β-sheet-like network as well as the segregation of hydrophobic amino acid residues into the interlayer space. The H-bonds add stability to the whole architecture while the hydrophobic groups keep the stacking layers at a distance that generates a cavity space available to a second component (encircled ""G"" in the Figure). A wide range of inclusions and co-crystals have been prepared in our group based on a series of dipeptides and higher peptide oligomers. For example, the incorporation of various organic solvents and bioactive molecules have been demonstrated for leucyl-alanine and similar dipeptides: alcohols, amides, phenols, pyridines, polyols, vitamins, scents and flavors. The crystal structure studies reveal a surprisingly persistent structural motif that can be used for engineering of crystalline materials with a specific property. We believe this type of peptide matrix may be utilized in the solid state organic synthesis [3] as reactive molecules of the second component can be oriented in a predictable way with respect to each other. "

NMR structure of bucandin, a neurotoxin from the venom of the Malayan krait (Bungarus candidus)

2001 ◽  
Vol 360 (3) ◽  
pp. 539-548 ◽  
Author(s):  
Allan M. TORRES ◽  
R. Manjunatha KINI ◽  
Nirthanan SELVANAYAGAM ◽  
Philip W. KUCHEL
Keyword(s):  
Solution Structure ◽  
Pharmacological Action ◽  
Nmr Structure ◽  
Side Chains ◽  
X Ray ◽  
Nmr Study ◽  
C Terminus ◽  
Mean Structure ◽  
Β Sheets ◽  
Β Sheet

A high-resolution solution structure of bucandin, a neurotoxin from Malayan krait (Bungarus candidus), was determined by 1H-NMR spectroscopy and molecular dynamics. The average backbone root-mean-square deviation for the 20 calculated structures and the mean structure is 0.47 Å (1 Å = 0.1nm) for all residues and 0.24 Å for the well-defined region that spans residues 23–58. Secondary-structural elements include two antiparallel β-sheets characterized by two and four strands. According to recent X-ray analysis, bucandin adopts a typical three-finger loop motif and yet it has some peculiar characteristics that set it apart from other common α-neurotoxins. The presence of a fourth strand in the second antiparallel β-sheet had not been observed before in three-finger toxins, and this feature was well represented in the NMR structure. Although the overall fold of the NMR structure is similar to that of the X-ray crystal structure, there are significant differences between the two structures that have implications for the pharmacological action of the toxin. These include the extent of the β-sheets, the conformation of the region spanning residues 42–49 and the orientation of some side chains. In comparison with the X-ray structure, the NMR structure shows that the hydrophobic side chains of Trp27 and Trp36 are stacked together and are orientated towards the tip of the middle loop. The NMR study also showed that the two-stranded β-sheet incorporated in the first loop, as defined by residues 1–22, and the C-terminus from Asn59, is probably flexible relative to the rest of the molecule. On the basis of the dispositions of the hydrophobic and hydrophilic side chains, the structure of bucandin is clearly different from those of cytotoxins.

Influence of Strand Number on Antiparallel β-Sheet Stability in Designed Three- and Four-stranded β-Sheets

2003 ◽  
Vol 326 (2) ◽  
pp. 553-568 ◽  
Author(s):  
Faisal A. Syud ◽  
Heather E. Stanger ◽  
Heather Schenck Mortell ◽  
Juan F. Espinosa ◽  
John D. Fisk ◽  
...  
Keyword(s):  
Β Sheets ◽  
Β Sheet

Cold smoking of Lebranche mullet (Mugil liza): Physicochemical, sensory, and microbiological evaluation

2020 ◽  
pp. 108201322095167
Author(s):  
Rolando Jimenez Lugo ◽  
Silvina Paola Agustinelli ◽  
María Isabel Yeannes ◽  
Marina Czerner
Keyword(s):  
Acetic Acid ◽  
Room Temperature ◽  
Microbial Growth ◽  
Stability Range ◽  
Overall Acceptability ◽  
Smoked Fish ◽  
Ph Values ◽  
Nacl Concentration ◽  
Salty Taste ◽  
Bacterial Groups

The suitability of Mugil liza for cold smoking was evaluated and the effect of four different salting treatments on physicochemical, microbiological, and sensory characteristics was assessed. The addition of sucrose (3%) and acetic acid (0.5%) to the brine lead to fillet dehydration with lower NaCl penetration, combined with higher reduction of pH. Brining at refrigerated temperature (5 ± 1 ℃) instead of room temperature (16 ± 2 ℃) was more effective in preventing microbial growth. Loads of bacterial groups assessed in all smoked samples were below 100 CFU/g and the aw, moisture, NaCl, and pH values achieved were within the typical stability range of smoked fish products. The obtained products were characterized by the smoked aroma and salty taste, differing in 7 of the 21 evaluated descriptors. The use of acetic acid in brine formulation showed an effect over color and texture descriptors. The affective test indicated the overall acceptability of products, being preferred the samples treated in the lowest NaCl concentration (5%).

scholarly journals Rippled β-Sheet Formation by an Amyloid-β Fragment Indicates Expanded Scope of Sequence Space for Enantiomeric β-Sheet Peptide Coassembly

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1983 ◽  
Author(s):  
Jennifer M. Urban ◽  
Janson Ho ◽  
Gavin Piester ◽  
Riqiang Fu ◽  
Bradley L. Nilsson
Keyword(s):  
Sequence Space ◽  
Self Assembly ◽  
Solid State Nmr ◽  
Amyloid Β ◽  
Amino Acid Residues ◽  
Hydrophobic Amino Acid ◽  
Amphipathic Peptide ◽  
Sequence Patterns ◽  
Β Sheets ◽  
Β Sheet

In 1953, Pauling and Corey predicted that enantiomeric β-sheet peptides would coassemble into so-called “rippled” β-sheets, in which the β-sheets would consist of alternating l- and d-peptides. To date, this phenomenon has been investigated primarily with amphipathic peptide sequences composed of alternating hydrophilic and hydrophobic amino acid residues. Here, we show that enantiomers of a fragment of the amyloid-β (Aβ) peptide that does not follow this sequence pattern, amyloid-β (16–22), readily coassembles into rippled β-sheets. Equimolar mixtures of enantiomeric amyloid-β (16–22) peptides assemble into supramolecular structures that exhibit distinct morphologies from those observed by self-assembly of the single enantiomer pleated β-sheet fibrils. Formation of rippled β-sheets composed of alternating l- and d-amyloid-β (16–22) is confirmed by isotope-edited infrared spectroscopy and solid-state NMR spectroscopy. Sedimentation analysis reveals that rippled β-sheet formation by l- and d-amyloid-β (16–22) is energetically favorable relative to self-assembly into corresponding pleated β-sheets. This work illustrates that coassembly of enantiomeric β-sheet peptides into rippled β-sheets is not limited to peptides with alternating hydrophobic/hydrophilic sequence patterns, but that a broader range of sequence space is available for the design and preparation of rippled β-sheet materials.

Structural Characterization of β-Lactoglobulin in Solution Using Two-Dimensional FT Mid-Infrared and FT Near-Infrared Correlation Spectroscopy

1997 ◽  
Vol 51 (4) ◽  
pp. 536-540 ◽  
Author(s):  
Nelson L. Sefara ◽  
Noel P. Magtoto ◽  
Hugh H. Richardson
Keyword(s):  
Near Infrared ◽  
Spectral Response ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
Helical Structures ◽  
Β Sheets ◽  
Α Helix ◽  
Combination Bands ◽  
Β Lactoglobulin ◽  
Β Sheet

Two-dimensional (2D) FT-IR correlation analysis was applied to both the mid-IR (MIR) and near-IR (NIR) regions to investigate changes in the secondary structures of β-lactoglobulin in D2O (or H2O) solvent systems consisting of varying concentrations of bromoethanol. Mid-IR correlation spectra indicate that the amide I bands corresponding to different structures (i.e., α-helical structures at 1650 cm−1, aggregated β-strands at 1620 cm−1, and β-sheet at 1636 cm−1) exhibit apparently different spectral response towards varying concentrations of bromoethanol. We propose that the mechanism for the conversion of the β-sheet into α-helix occurs in terms of two parallel pathways, i.e., (1) β-sheets → aggregated β-strands →α-helix, and (2) β-sheets →α-helix. Although the amide B/amide II combination bands give no spectral features relating to the secondary structure, changes were found in the C–H combination bands that suggest an interaction between the solvent and the protein.

Conformational preferences of β-sheet structures in cyclopropane-containing γ-peptides

2015 ◽  
Vol 39 (6) ◽  
pp. 4640-4646 ◽  
Author(s):  
Ji Hyang Lee ◽  
Hae Sook Park ◽  
Young Kee Kang
Keyword(s):  
Conformational Preferences ◽  
Cyclopropanecarboxylic Acid ◽  
Β Sheets ◽  
Β Sheet

Oligo-γ-peptides based on 2-(aminomethyl)cyclopropanecarboxylic acid (γAmc3) with a cyclopropane constraint on the Cα–Cβ bond preferentially formed parallel β-sheets rather than antiparallel β-sheets due to the stronger N–H⋯O H-bonds in the parallel conformation.

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