scholarly journals The effect of counterions on melittin aggregation

1983 ◽  
Vol 211 (3) ◽  
pp. 683-686 ◽  
Author(s):  
A S Tatham ◽  
R C Hider ◽  
A F Drake
Keyword(s):  
Aqueous Solution ◽  
Bee Venom ◽  
Random Coil ◽  
C Terminus ◽  
N Terminus ◽  
Surface Active ◽  
Α Helix

Melittin, a surface-active polypeptide from bee venom, has an overall hydrophobic N-terminus, with basic residues clustered at the C-terminus. In aqueous solution melittin exists as a mixture of monomer and tetramer, the monomer adopting a predominantly random-coil configuration, whereas the tetramer is rich in α-helix. The tendency of melittin to aggregate is dependent on the counter-anions present in solution, the effect being most marked with phosphate, decreasing in the order HPO4(2-) greater than SO4(2-) greater than ClO4- greater than Cl-.

The α-Helix Folds More Rapidly at the C-Terminus Than at the N-Terminus

2005 ◽  
Vol 127 (40) ◽  
pp. 13784-13785 ◽  
Author(s):  
Angela Pozo Ramajo ◽  
Sarah A. Petty ◽  
Agnieszka Starzyk ◽  
Martin Volk
Keyword(s):  
C Terminus ◽  
N Terminus ◽  
Α Helix

Reversible polypeptide hydrogels from asymmetric telechelics with temperature-dependent and Ni2+-dependent connectors

Soft Matter ◽  
2016 ◽  
Vol 12 (22) ◽  
pp. 4979-4984 ◽  
Author(s):  
Thao T. H. Pham ◽  
Jasper van der Gucht ◽  
J. Mieke Kleijn ◽  
Martien A. Cohen Stuart
Keyword(s):  
Triple Helix ◽  
Random Coil ◽  
Temperature Dependent ◽  
Self Assembling ◽  
C Terminus ◽  
N Terminus ◽  
Asymmetric Hybrid

An asymmetric (‘hybrid’) triblock polypeptide TR4H with two different, orthogonally self-assembling end blocks has been constructed by conjugating a long (37 kDa) random coil block (R4) with a triple helix former T = (Pro-Gly-Pro)9 at the N terminus, and a histidine hexamer (‘Histag’, H) at the C terminus.

Weitere Untersuchungen zur Aminosäuresequenz des Melittins

1969 ◽  
Vol 24 (1) ◽  
pp. 33-35 ◽  
Author(s):  
Joachim Jentsch
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Biological Activity ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Polypeptide Chain ◽  
Optical Rotatory Dispersion ◽  
Optical Rotatory ◽  
Surface Active ◽  
Α Helix

Melittin is the (main) toxic peptide of bee venom having a molecular weight of 2840, with a known sequence (s. fig. 1). Optical rotatory dispersion of non-crystalline melittin in aqueous solution suggests that the polypeptide chain is random, although 7% α-helix has been determined. These results are in agreement with the amino acid sequence of melittin and the assumption that the biological activity is attributable to its surface active character.

scholarly journals Structural and functional characterization of recombinant mouse annexin A11: influence of calcium binding

2003 ◽  
Vol 373 (2) ◽  
pp. 437-449 ◽  
Author(s):  
Emilio LECONA ◽  
Javier TURNAY ◽  
Nieves OLMO ◽  
Ana GUZMÁN-ARÁNGUEZ ◽  
Reginald O. MORGAN ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Tertiary Structure ◽  
Random Coil ◽  
Tryptophan Residue ◽  
Tyrosine Residues ◽  
Recombinant Mouse ◽  
Structural And Functional Properties ◽  
N Terminus ◽  
Annexin A11 ◽  
Α Helix

Annexin A11 is one of the 12 vertebrate subfamilies in the annexin superfamily of calcium/phospholipid-binding proteins, distinguishable by long, non-homologous N-termini rich in proline, glycine and tyrosine residues. As there is negligible structural information concerning this annexin subfamily apart from primary sequence data, we have cloned, expressed and purified recombinant mouse annexin A11 to investigate its structural and functional properties. CD spectroscopy reveals two main secondary-structure contributions, α-helix and random coil (approx. 30% each), corresponding mainly to the annexin C-terminal tetrad and the N-terminus respectively. On calcium binding, an increase in α-helix and a decrease in random coil are detected. Fluorescence spectroscopy reveals that its only tryptophan residue, located at the N-terminus, is completely exposed to the solvent; calcium binding promotes a change in tertiary structure, which does not affect this tryptophan residue but involves the movement of approximately four tyrosine residues to a more hydrophobic environment. These calcium-induced structural changes produce a significant thermal stabilization, with an increase of approx. 14 °C in the melting temperature. Annexin A11 binds to acidic phospholipids and to phosphatidylethanolamine in the presence of calcium; weaker calcium-independent binding to phosphatidylserine, phosphatidic acid and phosphatidylethanolamine was also observed. The calcium-dependent binding to phosphatidylserine is accompanied by an increase in α-helix and a decrease in random-coil contents, with translocation of the tryptophan residue towards a more hydrophobic environment. This protein induces vesicle aggregation but requires non-physiological calcium concentrations in vitro. A three-dimensional model, consistent with these data, was generated to conceptualize annexin A11 structure–function relationships.

EFFECT OF STORAGE TIME AND CONCENTRATION ON STRUCTURE OF REGENERATED SILK FIBROIN SOLUTION

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3878-3883 ◽  
Author(s):  
FANG XIE ◽  
HUILI SHAO ◽  
XUECHAO HU
Keyword(s):  
Aqueous Solution ◽  
Silk Fibroin ◽  
Storage Time ◽  
Conformational Transition ◽  
Solution Concentration ◽  
Cd Spectroscopy ◽  
Random Coil ◽  
Conformational Transformation ◽  
Regenerated Silk Fibroin ◽  
Α Helix

Concentrated regenerated silk fibroin (RSF) aqueous solutions with concentration close to that of the native silk fibroin (15.5%, 25.5% and 31%) were prepared. The effect of storage time and concentration on the conformational transition of the concentrated RSF aqueous solution was studied by Raman spectroscopy and circular dichroism (CD) spectroscopy. At the same time, the conformational change of RSF aqueous solution in flowing state was also investigated. It was found that the conformation of silk fibroin was changed gradually from random coil/α-helix to β-sheet structure during the storage. And the conformational transformation was accelerated with the increasing of the RSF aqueous solution concentration. When the solution was in flowing state, the conformational transformation was also accelerated.

scholarly journals N- and C-Terminal Cooperation in Rotavirus Enterotoxin: Novel Mechanism of Modulation of the Properties of a Multifunctional Protein by a Structurally and Functionally Overlapping Conformational Domain

2006 ◽  
Vol 80 (1) ◽  
pp. 412-425 ◽  
Author(s):  
M. R. Jagannath ◽  
M. M. Kesavulu ◽  
R. Deepa ◽  
P. Narayan Sastri ◽  
S. Senthil Kumar ◽  
...  
Keyword(s):  
Nonstructural Protein ◽  
Three Dimensional ◽  
Binding Activity ◽  
Dimensional Structure ◽  
Newborn Mouse ◽  
Multifunctional Protein ◽  
C Terminus ◽  
N Terminus ◽  
Α Helix ◽  
Pleiotropic Properties

ABSTRACT Rotavirus NSP4 is a multifunctional endoplasmic reticulum (ER)-resident nonstructural protein with the N terminus anchored in the ER and about 131 amino acids (aa) of the C-terminal tail (CT) oriented in the cytoplasm. Previous studies showed a peptide spanning aa 114 to 135 to induce diarrhea in newborn mouse pups with the 50% diarrheal dose approximately 100-fold higher than that for the full-length protein, suggesting a role for other regions in the protein in potentiating its diarrhea-inducing ability. In this report, employing a large number of methods and deletion and amino acid substitution mutants, we provide evidence for the cooperation between the extreme C terminus and a putative amphipathic α-helix located between aa 73 and 85 (AAH73-85) at the N terminus of ΔN72, a mutant that lacked the N-terminal 72 aa of nonstructural protein 4 (NSP4) from Hg18 and SA11. Cooperation between the two termini appears to generate a unique conformational state, specifically recognized by thioflavin T, that promoted efficient multimerization of the oligomer into high-molecular-mass soluble complexes and dramatically enhanced resistance against trypsin digestion, enterotoxin activity of the diarrhea-inducing region (DIR), and double-layered particle-binding activity of the protein. Mutations in either the C terminus, AAH73-85, or the DIR resulted in severely compromised biological functions, suggesting that the properties of NSP4 are subject to modulation by a single and/or overlapping highly sensitive conformational domain that appears to encompass the entire CT. Our results provide for the first time, in the absence of a three-dimensional structure, a unique conformation-dependent mechanism for understanding the NSP4-mediated pleiotropic properties including virus virulence and morphogenesis.

Preparation and Characterization of Wool Keratin/PVA Blended Films

2011 ◽  
Vol 175-176 ◽  
pp. 132-136 ◽  
Author(s):  
Ming Xia Gou ◽  
Xu Hong Yang
Keyword(s):  
Aqueous Solution ◽  
Random Coil ◽  
Ftir Analysis ◽  
Microscopy Investigation ◽  
Electron Microscopy Investigation ◽  
Scanning Electron Microscopy Investigation ◽  
Α Helix ◽  
Β Sheet ◽  
Wool Keratin

The method of extracting protein from wool was studied for the purpose of reusing the waste wool. The aqueous solution of wool keratin was prepared with Sodium Shlfide as reductive agent. In this paper, PVA was used to mix with keratin in different proportions. Both solutions were cast to obtain blended films. Scanning electron microscopy investigation showed that the surface of blended films was rough and uneven and the surface of the pure keratin film had small peridiole. FTIR analysis indicated that the secondary structure of the keratin was influenced by the blending ratios. Compared with wool fiber, the keratin film cast from aqueous solution showed a decrease in the amount of α-helix structure, while β-sheet and random coil conformations increased. When the keratin solution and PVA solution were blended in the ratios of 40:60, the film was flexible and rigid, and had good mechanical properties. This study encourages the further investigation of the applications of wool keratin films in the biomedical field, which could provide a new way to reuse various waste feathers.

Preparation and properties of three analogues of [5-leucine]enkephalin, substrates for enzyme conversion studies

1985 ◽  
Vol 50 (6) ◽  
pp. 1329-1334
Author(s):  
Jaroslav Vičar ◽  
Linda Servítová ◽  
Martin Flegel ◽  
Karel Hauzer ◽  
Tomislav Barth
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Guinea Pig ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Guinea Pig Ileum ◽  
Opioid Activity ◽  
C Terminus ◽  
N Terminus ◽  
Fragment Condensation

Analogues of [5-Leu]enkephalin, prolonged by methionine on the N-terminus or, by lysine or methionine on the C-terminus were prepared by fragment condensation, purified by ion exchange chromatography or high-pressure liquid chromatography. The substances were characterised by their opioid activity in a test on guinea-pig ileum in comparison with the activity of [5-Leu]enkephalin.

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