The self-association of the cyclotide kalata B2 in solution is guided by hydrophobic interactions

Biopolymers ◽  
2013 ◽  
Vol 100 (5) ◽  
pp. 453-460 ◽  
Author(s):  
K. Johan Rosengren ◽  
Norelle L. Daly ◽  
Peta J. Harvey ◽  
David J. Craik
Keyword(s):  
Hydrophobic Interactions ◽  
The Self ◽  
Self Association

scholarly journals Erratum: The self-association of the cyclotide kalata B2 in solution is guided by hydrophobic interactions

Biopolymers ◽  
2013 ◽  
Vol 102 (1) ◽  
pp. 136-136
Author(s):  
K. Johan Rosengren ◽  
Norelle L. Daly ◽  
Peta J. Harvey ◽  
David J. Craik
Keyword(s):  
Hydrophobic Interactions ◽  
The Self ◽  
Self Association

Hydrophobic Interactions in Solution: A Nuclear Magnetic Resonance Approach

2000 ◽  
Vol 214 (7) ◽  
Author(s):  
A. Sacco
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Hydrophobic Interactions ◽  
The Self ◽  
Aqueous Mixtures ◽  
Organic Components ◽  
Self Association ◽  
Small Hydrophobic ◽  
Nuclear Magnetic

The self-association behaviour of relatively small hydrophobic organic components in aqueous mixtures has been investigated by the application of an NMR technique. The association A

scholarly journals The interplay of self-assembly and target binding in centrin 1 from Toxoplasma gondii

2021 ◽  
Author(s):  
Carolina Conter ◽  
Luca Bombardi ◽  
Marco Pedretti ◽  
Filippo Favretto ◽  
Adele Di Matteo ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Self Assembly ◽  
Metal Binding ◽  
Hydrophobic Interactions ◽  
Structural Features ◽  
The Self ◽  
Intact Protein ◽  
Titration Calorimetry ◽  
Self Association ◽  
Target Binding

Centrins are conserved calcium (Ca2+)-binding proteins typically associated with centrosomes that have been implicated in several biological processes. In Toxoplasma gondii, a parasite that causes toxoplasmosis, three centrin isoforms have been recognized. We have recently characterized the metal binding and structural features of isoform 1 (TgCEN1), demonstrating that it possesses properties consistent with a role as a Ca2+ sensor and displays a Ca2+-dependent tendency to self-assemble. Herein, we expanded our studies, focusing on the self-association and target binding properties of TgCEN1 by combining biophysical techniques including dynamic light scattering, isothermal titration calorimetry, nuclear magnetic resonance, circular dichroism, and fluorescence spectroscopy. We found that the self-assembly process of TgCEN1 depends on different physicochemical factors, including Ca2+ concentration, temperature, and protein concentration, and is mediated by both electrostatic and hydrophobic interactions. The process is completely abolished upon removal of the first 21-residues of the protein and is significantly reduced in the presence of a binding target peptide derived from the human XPC protein (P17-XPC). Titration of P17-XPC to the intact protein and isolated domains showed that TgCEN1 possesses two binding sites with distinct affinities and Ca2+ sensitivity; a high-affinity site in the C-lobe which may be constitutively bound to the peptide and a low-affinity site in the N-lobe which is active only upon Ca2+ stimulus. Overall, our results suggest a specific mechanism of TgCEN1 for Ca2+-modulated target binding and support a N-to-C self-assembly mode, in which the first 21-residues of one molecule likely interact with the C-lobe of the other.

The self-association of naturally occurring purine nucleoside 5′-monophosphates in aqueous solution

1979 ◽  
Vol 57 (15) ◽  
pp. 1986-1994 ◽  
Author(s):  
Klaus J. Neurohr ◽  
Henry H. Mantsch
Keyword(s):  
Aqueous Solution ◽  
Hydrophobic Interactions ◽  
Equilibrium Constants ◽  
The Self ◽  
Purine Nucleoside ◽  
Base Stacking ◽  
H Nmr ◽  
Induced Dipole ◽  
Stacking Pattern ◽  
Self Association

The parameters characterizing the base-stacking self-association of adenosine, inosine, and guanosine 5′-monophosphate have been obtained from 1H nmr dilution studies. The thermodynamic parameters for the formation of adenosine 5′-monophosphate stacks are ΔH0 = −14.5 kJ mol−1 and ΔS0 = −42.3 J K−1 mol−1, with an apparent equilibrium constant of Kc = 1.92 M−1 at 30 °C. The corresponding equilibrium constants for the self-association of inosine and guanosine 5′-monophosphate are 1.36 M−1 and 1.29 M−1, respectively. The negative enthalpy and entropy changes cannot be explained by the concept of classical hydrophobic interactions; however, they strongly support the conclusion that dipole induced dipole forces play a major role for base-stacking in aqueous solution. The sequence of the equilibrium constants for the purine nucleoside 5′-monophosphates can be well explained by the concept of mutual polarization. The stacking geometries for adenosine and inosine 5′-monophosphate are presented as obtained from fitting the experimental shift data to refined isoshielding contours. It is concluded that the stacking pattern is not restricted to a unique geometry.

Dynamic molecular modeling of pathogenic mutations in the spectrin self-association domain

Blood ◽  
2001 ◽  
Vol 98 (6) ◽  
pp. 1645-1653 ◽  
Author(s):  
Zhushan Zhang ◽  
Scott A. Weed ◽  
Patrick G. Gallagher ◽  
Jon S. Morrow
Keyword(s):  
Hydrophobic Interactions ◽  
Repeat Unit ◽  
Point Mutations ◽  
The Self ◽  
Dimensional Structure ◽  
Salt Bridges ◽  
3 Dimensional ◽  
Human Sequence ◽  
Clinical Consequences ◽  
Self Association

Abstract Disruption of spectrin self-association underlies many inherited hemolytic disorders. Using dynamic modeling and energy minimization, the 3-dimensional structure of the self-association domain has been estimated in human erythrocyte spectrin and the structural consequences of 17 elliptogenic mutations determined. The predicted structure of the normal self-association domain was remarkably similar to the crystal structure of the Drosophila α-spectrin 14th repeat unit, despite replacement in the human sequence of over 70% of the amino acids relative to fly spectrin, including 2 prolines in the human sequence that appear in helical regions of the fly structure. The predicted structure placed all hydrophilic residues at the surface and identified 4 salt bridges, 9 hydrophobic interactions, and 4 H-bonds that stabilize the native self-association unit. Remarkably, every pathologic point mutation, including seemingly conservative substitutions such as G for A, A for V, or K for R (single-letter amino acid codes), led to conformational rearrangements in the predicted structure. The degree of structural disruption, as measured by root-mean-square deviation of the predicted backbone structure from theDrosophila structure, correlated strongly with the severity of clinical disease associated with each mutation. This approach thus enables an accurate prediction, from the primary sequence, of the clinical consequences of specific point mutations in spectrin. The 3-dimensional structure of the self-association domain derived here is likely to be accurate. It provides a powerful heuristic model for understanding how point mutations disrupt cytoskeletal function in a variety of hemolytic disorders.

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