Search results for "folding"
showing 10 items of 330 documents
Influence of the hydrophilic face on the folding ability and stability of α-helix bundles: relevance to the peptide catalytic activity
2000
Although not the sole feature responsible, the packing of amino acid side chains in the interior of proteins is known to contribute to protein conformational specificity. While a number of amphipathic peptide sequences with optimized hydrophobic domains has been designed to fold into a desired aggregation state, the contribution of the amino acids located on the hydrophilic side of such peptides to the final packing has not been investigated thoroughly. A set of self-aggregating 18-mer peptides designed previously to adopt a high level of alpha-helical conformation in benign buffer is used here to evaluate the effect of the nature of the amino acids located on the hydrophilic face on the pa…
Chapter 16 Folding and Pigment Binding of Light-Harvesting Chlorophyll a/b Protein (LHCIIb)
2010
The major light-harvesting chlorophyll a/b protein (LHCIIb) is one of the most abundant proteins of the chloroplast in green plants. It contains roughly half of the chlorophylls involved in photosynthesis, and exhibits an unusual ability to self-organize in vitro. Simply mixing the apoprotein, native or recombinant, with its pigments, chlorophyll a, chlorophyll b, and xanthophylls, in detergent solution, suffices to trigger protein folding and the assembly of about 18 pigments in their correct binding sites. A study of the mechanism of this self-organization seems worthwhile since (1) our knowledge about membrane protein folding is scarce compared to what we know about the folding of water-…
The Crystalline State of Macromolecular Substances
1974
Unlike low molecular weight substances, high polymers do not crystallize completely. However long the crystallization process is continued, they still consist of a mixture of crystalline and non crystalline regions. In the undrawn material, these regions form larger units which are known as spherulites. Questions that are of special interest concern the arrangement of the chains in the noncrystalline regions, the causes of chain folding, and the imperfections in the crystals. The incomplete crystallization is a consequence of kinetic inhibitions. This can be deduced from the fact that the crystalline fraction increases with rising crystallization temperature. If polymerization is carried ou…
Crystal structure of the bifunctional soybean Bowman-Birk inhibitor at 0.28-nm resolution. Structural peculiarities in a folded protein conformation.
1996
The Bowman-Birk inhibitor from soybean is a small protein that contains a binary arrangement of trypsin-reactive and chymotrypsin-reactive subdomains. In this report, the crystal structure of this anticarcinogenic protein has been determined to 0.28-nm resolution by molecular replacement from crystals grown at neutral pH. The crystal structure differs from a previously determined NMR structure [Werner, M. H. & Wemmer, D. E. (1992) Biochemistry 31, 999-1010] in the relative orientation of the two enzyme-insertion loops, in some details of the main chain trace, in the presence of favourable contacts in the trypsin-insertion loop, and in the orientation of several amino acid side chains. The p…
Facile access to foldable redox-active flavin-peptide conjugates
2021
A convenient approach for the synthesis of foldable redox-active flavin peptide conjugates was established. A model β-hairpin oligopeptide motif was utilized to demonstrate that azidolysine side-chains are readily functionalised with an alkyne-bearing flavine derivative. The folding equilibrium of the peptide backbone as well as the redox behaviour of the flavin moieties remains intact after the conjugation.
Comparative analysis of the coordinated motion of Hsp70s from different organelles observed by single-molecule three-color FRET.
2021
Cellular function depends on the correct folding of proteins inside the cell. Heat-shock proteins 70 (Hsp70s), being among the first molecular chaperones binding to nascently translated proteins, aid in protein folding and transport. They undergo large, coordinated intra- and interdomain structural rearrangements mediated by allosteric interactions. Here, we applied a three-color single-molecule Forster resonance energy transfer (FRET) combined with three-color photon distribution analysis to compare the conformational cycle of the Hsp70 chaperones DnaK, Ssc1, and BiP. By capturing three distances simultaneously, we can identify coordinated structural changes during the functional cycle. Be…
Combinatorial chemistry of -hairpins
2000
Combinatorial chemistry is expanding rapidly both in terms of chemistry development and application to the synthesis of compound libraries for lead discovery and optimization. Combinatorial technologies continue evolving and developing, in fact they are being used as basic research tools in different fields that include peptide/protein folding. This review examines the use of combinatorial chemistry in the design of peptides and protein domains that adopt beta-sheet conformations. In particular, the use of conformationally restricted peptide libraries has allowed the identification of linear peptides that are folded in a beta-hairpin structure in plain aqueous solutions.
Design of bioactive and structurally well-defined peptides from conformationally restricted libraries
2004
Libraries of peptides and proteins can be categorized according to the function of their origin in gene- and synthetic-based libraries. Both kinds of libraries have the potential to generate the same grade of molecular diversity, although the limits imposed by the synthetic methods have been lately a matter of discussion. However, the use of synthetic strategies allows incorporation of non-natural amino acids. The development of canfonnallonally restricted synthetic peptide libraries can be considered as a point of convergence of the two methodologies. In these libraries the diversity is grafted into scaffolds that are defined by stable secondary structural motifs, and the deconvolution pro…
Pigment ligation to proteins of the photosynthetic apparatus in higher plants
1997
Ligation of pigments to proteins of the thylakoid membrane is a central step in the assembly of the photosynthetic apparatus in higher plants. Because of the potentially damaging photooxidative activity of chlorophylls, it is likely that between their biosynthesis and final assembly, chlorophylls will always be bound to protein complexes in which photooxidation is prevented by quenchers such as carotenoids. Such complexes may include chlorophyll carriers and/or membrane receptors involved in protein insertion into the membrane. Many if not all pigment-protein complexes of the thylakoid are stabilised towards protease attack by bound pigments. The major light-harvesting chlorophyll a/b prote…
Guest-Induced Folding and Self-Assembly of Conformationally Adaptive Macrocycles into Nanosheets and Nanotubes
2017
A conformationally adaptive macrocycle is presented, namely zorb[4]arene, which exists in multiple conformations in the uncomplexed state. The binding cavity of zorb[4]arene is concealed, either due to a collapsed conformation or by self-inclusion. The zorb[4]arene with long alkyl chains manifests itself with surprisingly low melting point and thus exist as an oil at room temperature. Binding of a guest molecule induces the folding and conformational rigidity of zorb[4]arene and leads to well-defined three-dimensional structures, which can further self-assemble into nanosheets or nanotubes upon solvent evaporation, depending on guest molecules and the conformations they can induce.