Search results for "Protein secondary structure"
showing 10 items of 88 documents
High Resolution Solution NMR Structure of the Z Domain of Staphylococcal Protein A. Analysis of Secondary Structure for Free Z Domain and Bounded to …
1997
Staphylococcal protein A (SpA) is a cell-wall-bound pathogenicity factor from the bacterium Staphylcoccus aureus. It exhibits tight binding to many IgG, IgA and IgM molecules at site(s) different from antigen-combining site. Because of their small size and immunoglobulin (IgG)-binding activities, domains of protein A are important targets for protein engineering efforts and for the development of computational approaches for de novo protein folding.
Drug Binding Properties of Tyrosine-Modified Human Serum Albumin
1978
Human serum albumin (HSA) has only a small number of specific binding sites for drugs. There are facts indicating that tyrosine residues may be involved in these binding sites. Thus we modified HSA with tetranitromethan, a reagent specific for tyrosine residues in proteins. As derived from an UV-absorption quotient three albumins with a degree of modification of two, five and eight residues per molecule were obtained. Only for the albumin with eight residues modified a small reduction of ordered secondary structure was found.
C2-Symmetric Ferrocene-Bis(ureido)peptides : Synthesis, Conformation and Solid-State Structure
2009
The extension of peptide derivatives of ferrocene-1,1'-dicarboxylic acid by formal insertion of NH units between ferrocene and peptide strands results in ferrocene-bis(ureido)-peptides. Experimentally, alanine and dialanine methyl esters were attached to the 1- and 1'-position of 1,1'-diiso-cyanoferrocene to give the corresponding bis(ureido)peptide derivatives 3 and 4. The conformation of 3 has been determined in the solid state by X-ray crystallography. In solution the preferred conformation of 3 and 4 has been elucidated by NMR, IR and CD spectroscopy in concert with DFT calculations. The secondary structure of ferrocene―bis(ureido)peptides 3 and 4 is determined by double bifurcated intr…
Pigment-pigment interactions and secondary structure of reconstituted algal chlorophyll a/b-binding light-harvesting complexes of Chlorella fusca wit…
1995
Earlier we have shown by in vitro reconstitution experiments that the pigment composition of the chlorophyll alb-binding light-harvesting complex of the green alga Chlorella fusca could be altered in a relatively broad range (Meyer and Wilhelm 1993). In this study we used these reconstituted complexes of different pigment loading to analyze the excitonic interactions between the pigment molecules and the secondary structure by means of circular dichroism spectra in the visible and the far UV spectral regions, respectively. We found that, in contrast to the expectations, the pigment composition and pigment content hardly affected the circular dichroism spectra in the visible spectral region.…
Stabilization of an ?-helical conformation in an isolated hexapeptide inhibitor of calmodulin
2001
The conformational properties of two hexapeptides, Ac-LWRILW-NH(2) and its D-amino acid counterpart Ac-lwrilw-NH(2), identified as calmodulin inhibitors using mixture-based synthetic combinatorial library approaches, have been characterised by NMR and CD spectroscopy. The peptides fold into an alpha-helical conformation in aqueous solution. The observed short- and medium-range nuclear Overhauser effects were consistent with the formation of an alpha-helical structure and a reasonably well-defined set of structures was obtained by using restraints from the NMR data in simulated annealing calculations. Analysis of glycine-substitution analogues demonstrated that all the amino acids that make …
Inhibition of cyclodextrins on α-galactosidase.
2017
This work successfully investigated the effects of different influential factors and hydrophobic cavities of cyclodextrins (CDs) on α-galactosidase (α-Gal) by detecting α-Gal activity. The highest inhibitory concentration of three kinds of CDs (α-, β-, and γ-CD) on α-Gal was 10mM. Moreover, the highest inhibition of α-Gal was obtained under the following conditions: reaction time of 90min, temperature of 30°C, and pH 6.0. Compared with other CDs, β-CD showed more ability to interact with α-Gal due to its appropriate cavity geometric dimensions. From circular dichroism and nuclear magnetic resonance it was observed that β-CD changed the secondary structure of α-Gal and formed a hydrogen bond…
Revisiting Secondary Structures in NCA Polymerization: Influences on the Analysis of Protected Polylysines
2014
Two series (degree of polymerization: 20–200) of polylysines with Z and TFA protecting groups were synthesized, and their behavior in a range of analytical methods was investigated. Gel permeation chromatography of the smaller polypeptides reveals a bimodal distribution, which is lost in larger polymers. With the help of GPC, NMR, circular dichroism (CD), and MALDI-TOF, it was demonstrated that the bimodal distribution is not due to terminated chains or other side reactions. Our results indicate that the bimodality is caused by a change in secondary structure of the growing peptide chain that occurs around a degree of polymerization of about 15. This change in secondary structure interferes…
Protein Unfolding:1H-NMR Studies of Paramagnetic Ferricytochrome c-550 from Horse Heart
2005
Electronic transfer protein cytochrome c-550 from horse heart is studied in the unfolded state by means of paramagnetic 1H NMR. The protein contains 104 aminoacid residues and a heme group with low spin FeIII ion in the oxidized form of protein. The global secondary structure is of the α-helix type as occurs in the case of very other cytochromes c investigated such as cyt c-550 from Thiobacillus versutus or cyt c-551 from Pseudomonas aeruginosa. We have studied the coordination characteristic and electronic properties of heme iron horse heart ferricytochrome c-550 at increasing denaturing conditions (up to 3.1 M GuHCl and 288-323 K). The 1H T1 values of the signals were measured and some re…
Impact of O → S Exchange in Ferrocenyl Amides on the Structure and Redox Chemistry
2014
The conformations and redox chemistry of ferrocenyl amides have been investigated in considerable depth in the last few years, while ferrocenyl thioamides have attracted less interest so far, although distinctly different conformations and reactivity patterns are expected. Monoferrocenyl amides Fc-NHC(O)CH3 (1) and 1,1′-CH3O(O)C-Fn-NHC(O)CH3 (2) and diferrocenyl amides Fc-NHC(O)-Fc (5) and Fc-NHC(O)-Fn-NHC(O)CH3 (6) are easily transformed into the corresponding thioamides (3, 4, 7, 8) by treatment with Lawesson’s reagent (2,4-bis(p-methoxyphenyl)-1,3-dithiaphosphetane-2,4-disulfide) (Fc = Fe(C5H4)(C5H5), Fn = Fe(C5H4)2). The thioamide conformations (cis/trans) in 3, 4, 7, and 8 and the hydr…
Conformational stability of oligoferrocene oligoamide foldamers
2016
Abstract Organometallic oligoamides built from three to four ferrocene amino acid units ( H-Fca-OH , 1-amino-1′-ferrocene carboxylic acid) fold into hydrogen bonded secondary structures featuring eight-membered rings by cooperative hydrogen bonds. NMR studies and DFT calculations (CAM-B3LYP, LANL2DZ, IEFPCM (THF)) reveal that the organometallic zigzag foldamer structures are highly resistant toward denaturation by hydrogen bond acceptors such as dimethyl sulfoxide and 2,4-lutidine. Replacing one ferrocene amino acid unit by the organic α -amino acid glycine at the C -terminal end (Fca → Gly) significantly destabilizes the secondary zigzag structure facilitating denaturation by DMSO. Highly …