scholarly journals Intrinsic α-helical and β-sheet conformational preferences: A computational case study of alanine

2014 ◽  
Vol 23 (7) ◽  
pp. 970-980 ◽  
Author(s):  
Diego Caballero ◽  
Jukka Määttä ◽  
Alice Qinhua Zhou ◽  
Maria Sammalkorpi ◽  
Corey S. O'Hern ◽  
...  
Keyword(s):  
Conformational Preferences ◽  
Β Sheet

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.

Dissolution of Amyloid Aggregates in Aqueous Ionic Liquid Solutions: A Case Study of Insulin Amyloid

2019 ◽  
Vol 72 (2) ◽  
pp. 81 ◽  
Author(s):  
Takahiro Takekiyo ◽  
Yuka Ishikawa ◽  
Erika Yamaguchi ◽  
Natsuki Yamada ◽  
Yukihiro Yoshimura
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Bovine Insulin ◽  
Future Design ◽  
Amyloid Aggregates ◽  
Liquid Solutions ◽  
The Difference ◽  
Β Sheet

Dissolution of amyloid aggregates with high β-sheet content is required for the correct refolding of ordered protein aggregates. The dissolution of bovine insulin amyloid aggregates in five different ionic liquids (ILs) is investigated. These were comprised of three 1-butyl-3-methylimidazolium ([bmim])-based ILs, containing either SCN−, NO3−, or Cl− anions, and two alkylammonium nitrate-based ILs, ethyl- and propylammonium nitrate (EAN and PAN). A broad IL concentration range (x=0–30mol-% IL) was analysed using FTIR spectroscopy combined with the Congo red assay. On the whole, the [bmim]-based ILs showed a higher dissolution ability than EAN and PAN for all concentrations of x. It is notable that the dissolution ability of dilute aqueous IL solutions (x<15) for insulin amyloid was different to that of concentrated aqueous IL solutions (x>15). The former condition for insulin amyloid may affect dissolution based on the denaturant effect of cations and anions in the ILs. The latter condition may affect this dissolution based on the hydrogen-bonding ability (α and β values) of the ILs, as described by the Kamlet–Taft parameters. Moreover, the difference between these α and β values (α–β) was found to be a good indicator of the dissolution ability of ILs for insulin amyloid aggregates in concentrated conditions above x=20 (α–β<0, strong dissolution ability; α–β>0, weak dissolution ability). These findings may assist the future design of aqueous IL-based dissolution agents for ordered aggregated proteins.

Conformational Preferences of Aβ25-35 and Aβ35-25 in Membrane Mimicking Environments

2019 ◽  
Vol 26 (5) ◽  
pp. 386-390
Author(s):  
Dhandayuthapani Sambasivam ◽  
Senthilkumar Sivanesan ◽  
Sayeeda Sultana ◽  
Jayakumar Rajadas
Keyword(s):  
Structural Transition ◽  
Conformational Transition ◽  
The Other ◽  
Random Coil ◽  
Structural Modifications ◽  
Sds Micelles ◽  
Conformational Preferences ◽  
Helix Conformation ◽  
Α Helix ◽  
Β Sheet

Background: The structural transition of aggregating Abeta peptides is the key event in the progression of Alzheimer’s Disease (AD). Objective: In the present work, the structural modifications of toxic Aβ25-35 and the scrambled Aβ35-25 were studied in Trifluoroethanol (TFE) and in aqueous SDS micelles. Methods: Using CD spectroscopic investigations, the conformational transition of Aβ25-35 and Aβ35-25 peptides were determined in different membrane mimicking environments such as TFE and SDS. An interval scan CD of the peptides on evaporation of TFE was performed. TFE titrations were carried out to investigate the intrinsic ability of the structural conformations of peptides. Results: We show by spectroscopic evidence that Aβ25-35 prefers beta sheet structures upon increasing TFE concentrations. On the other hand, the non-toxic scrambled Aβ35-25 peptide only undergoes a transition from random coil to α-helix conformation with increasing TFE. In the interval scan studies, Aβ25-35 did not show any structural transitions, whereas Aβ35-25 showed transition from α-helix to β-sheet conformation. In membrane simulating aqueous SDS micelles, Aβ25-35 showed a transition from random coil to α-helix while Aβ35-25 underwent transition from random coil to β-sheet conformation. Conclusion: Overall, the current results seek new insights into the structural properties of amyloidogenic and the truncated sequence in membrane mimicking solvents.

Synthesis, Reactivity and Conformational Preferences of Novel Enediynyl Peptides: A Possible Scaffold for β-Sheet Capping Turns.

ChemInform ◽  
2003 ◽  
Vol 34 (2) ◽  
Author(s):  
Amit Basak ◽  
Kakali Rani Rudra ◽  
Subhendu Sekhar Bag ◽  
Ajoy Basak
Keyword(s):  
Conformational Preferences ◽  
Β Sheet

scholarly journals Identification of drivers for the metamorphic transition of HIV-1 reverse transcriptase

2017 ◽  
Vol 474 (19) ◽  
pp. 3321-3338 ◽  
Author(s):  
Xunhai Zheng ◽  
Geoffrey A. Mueller ◽  
Kyungmin Kim ◽  
Lalith Perera ◽  
Eugene F. DeRose ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Hydrophobic Surface ◽  
Terminal Segment ◽  
Nmr Studies ◽  
Conformational Preferences ◽  
Starting Point ◽  
Immunodeficiency Virus ◽  
Β Sheet ◽  
Structural Characterizations ◽  
Hiv 1

Recent structural characterizations of the p51 and p66 monomers have established an important starting point for understanding the maturation pathway of the human immunodeficiency virus (HIV)-1 reverse transcriptase p66/p51 heterodimer. This process requires a metamorphic transition of the polymerase domain leading to formation of a p66/p66′ homodimer that exists as a structural heterodimer. To better understand the drivers for this metamorphic transition, we have performed NMR studies of 15N-labeled RT216 — a construct that includes the fingers and most of the palm domains. These studies are consistent with the conclusion that the p66 monomer exists as a spring-loaded complex. Initial dissociation of the fingers/palm : connection complex allows the fingers/palm to adopt an alternate, more stable structure, reducing the rate of reassociation and facilitating subsequent maturation steps. One of the drivers for an initial extension of the fingers/palm domains is identified as a straightening of helix E relative to its conformation in the monomer by eliminating a bend of ∼50° near residue Phe160. NMR and circular dichroism data also are consistent with the conclusion that a hydrophobic surface of palm domain that becomes exposed after the initial dissociation, as well as the intrinsic conformational preferences of the palm domain C-terminal segment, facilitates the formation of the β-sheet structure that is unique to the active polymerase subunit. Spectral comparisons based on 15N-labeled constructs are all consistent with previous structural conclusions based on studies of 13C-methyl-labeled constructs.

The Genesis and Internal Dynamics of El Salvador's People's Revolutionary Army, 1970–1976

2014 ◽  
Vol 38 (01) ◽  
pp. 102-129
Author(s):  
ALBERTO MARTÍN ÁLVAREZ ◽  
EUDALD CORTINA ORERO
Keyword(s):  
Latin America ◽  
El Salvador ◽  
Early Years ◽  
Left Wing ◽  
Internal Dynamics ◽  
Internal Coherence ◽  
The 1960S

AbstractUsing interviews with former militants and previously unpublished documents, this article traces the genesis and internal dynamics of the Ejército Revolucionario del Pueblo (People's Revolutionary Army, ERP) in El Salvador during the early years of its existence (1970–6). This period was marked by the inability of the ERP to maintain internal coherence or any consensus on revolutionary strategy, which led to a series of splits and internal fights over control of the organisation. The evidence marshalled in this case study sheds new light on the origins of the armed Salvadorean Left and thus contributes to a wider understanding of the processes of formation and internal dynamics of armed left-wing groups that emerged from the 1960s onwards in Latin America.

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