Synthesis and chiroptical properties of heterodetic cyclic hexapeptides related to oxytocin ring moiety

1980 ◽  
Vol 45 (4) ◽  
pp. 1109-1131 ◽  
Author(s):  
Ivo Frič ◽  
Lyudmila I. Leonteva ◽  
Petr Maloň ◽  
Karel Jošt ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Peptide Synthesis ◽  
Spatial Arrangement ◽  
Cd Spectroscopy ◽  
Side Chains ◽  
Peptide Backbone ◽  
Chiroptical Properties ◽  
Disulfide Group ◽  
Cyclic Hexapeptides

Cyclic disulfides of cysteinyl-tetraglycyl-cysteine (Ia), cysteinyl-tyrosyl-triglycyl-cysteine (Ib) and cysteinyl-tyrosyl-isoleucyl-diglycyl-cysteine (Ic) were synthesized by classical methods of peptide synthesis. The actions of solvent and of side chains in the positions 2 and 3 on the conformational arrangement of the peptide backbone and the disulfide group were investigated by means of CD spectroscopy. Some mechanisms which co-operate in stabilizing the oxytocin conformation were identified. Hence, it may be deduced, that the amino acid sequence in the positions 1-3 determines the spatial arrangement characteristic for oxytocin, at least in a protonating medium.

A Strategy for Thioamide Incorporation During Fmoc Solid-Phase Peptide Synthesis with Robust Stereochemical Integrity

2019 ◽  
Author(s):  
luis camacho III ◽  
Bryan J. Lampkin ◽  
Brett VanVeller
Keyword(s):  
Amino Acid ◽  
Functional Groups ◽  
Peptide Synthesis ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Side Chains ◽  
Amino Acid Side Chains ◽  
Peptide Elongation

We describe a method to protect the sensitive stereochemistry of the thioamide—in analogy to the protection of the functional groups of amino acid side chains—in order to preserve the thioamide moiety during peptide elongation.<br>

Weitere Untersuchungen zur Aminosäuresequenz des Melittins, II.

1969 ◽  
Vol 24 (4) ◽  
pp. 415-418 ◽  
Author(s):  
Joachim Jentsch
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
High Specificity ◽  
Bee Venom ◽  
Side Chains ◽  
Amino Groups ◽  
Crotalus Atrox ◽  
Peptide Bonds ◽  
Rattlesnake Venom

Degradation of melittin with α-Protease from Crotalus atrox venom (rattlesnake) confirmed the amino acid sequence of the toxic main peptide from bee venom. Hydrolysis occured mainly at the peptide bonds whose amino groups were provided by hydrophobic side chains such as valine, leucine and isoleucine bonds. However, on the contrary one glutamine bond was cleaved. Neverthelness, regarding the relatively high specificity, rattlesnake venom protease may be a valuable reagent for further sequence studies.

Peptide Backbone Effect on Hydration Free Energies of Amino Acid Side Chains

2014 ◽  
Vol 118 (46) ◽  
pp. 13162-13168 ◽  
Author(s):  
Timir Hajari ◽  
Nico F. A. van der Vegt
Keyword(s):  
Amino Acid ◽  
Side Chains ◽  
Free Energies ◽  
Peptide Backbone ◽  
Amino Acid Side Chains

Three cyclohexapeptides modelling the oxytocin ring moiety: Synthesis and circular dichroism

1987 ◽  
Vol 52 (7) ◽  
pp. 1841-1856 ◽  
Author(s):  
Jan Hlaváček ◽  
Ivo Frič ◽  
Petr Maloň ◽  
Karel Jošt ◽  
Karel Bláha
Keyword(s):  
Circular Dichroism ◽  
Conformational Mobility ◽  
Side Chains ◽  
Polar Solvents ◽  
Peptide Backbone ◽  
Specific Solvation ◽  
Disulfide Group ◽  
Peptide Moiety ◽  
Circular Dichroïsm

A series of cyclic disulfides cysteinyl-triglycyl-asparaginyl-cysteine (Ib), cysteinyl-diglycyl-glutaminyl-asparaginyl-cysteine (Ic), and cysteinyl-glycyl-isoleucyl-glutaminyl-asparaginyl-cysteine (Id) has been prepared. The effect of gradual attachment of side chains to the ring on the peptide backbone and the disulfide group conformation has been studied using circular dichroism. Introduction of side chains reduces substantially the conformational mobility of the backbone , but not enough to let any conformational β-turn type predominate (in polar solvents). Conformation of the disulfide group is essentially independent of the peptide moiety of the molecule and is influenced by specific solvation.

scholarly journals Role of pKA in Charge Regulation and Conformation of Various Peptide Sequences

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 214
Author(s):  
Raju Lunkad ◽  
Anastasiia Murmiliuk ◽  
Zdeněk Tošner ◽  
Miroslav Štěpánek ◽  
Peter Košovan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Coarse Grained ◽  
Disordered Proteins ◽  
Total Charge ◽  
Side Chains ◽  
Intrinsically Disordered ◽  
Acid And Base ◽  
Base Side

Peptides containing amino acids with ionisable side chains represent a typical example of weak ampholytes, that is, molecules with multiple titratable acid and base groups, which generally exhibit charge regulating properties upon changes in pH. Charged groups on an ampholyte interact electrostatically with each other, and their interaction is coupled to conformation of the (macro)molecule, resulting in a complex feedback loop. Their charge-regulating properties are primarily determined by the pKA of individual ionisable side-chains, modulated by electrostatic interactions between the charged groups. The latter is determined by the amino acid sequence in the peptide chain. In our previous work we introduced a simple coarse-grained model of a flexible peptide. We validated it against experiments, demonstrating its ability to quantitatively predict charge on various peptides in a broad range of pH. In the current work, we investigated two types of peptide sequences: diblock and alternating, each of them consisting of an equal number of amino acids with acid and base side-chains. We showed that changing the sequence while keeping the same overall composition has a profound effect on the conformation, whereas it practically does not affect total charge on the peptide. Nevertheless, the sequence significantly affects the charge state of individual groups, showing that the zero net effect on the total charge is a consequence of unexpected cancellation of effects. Furthermore, we investigated how the difference between the pKA of acid and base side chains affects the charge and conformation of the peptide, showing that it is possible to tune the charge-regulating properties by following simple guiding principles based on the pKA and on the amino acid sequence. Our current results provide a theoretical basis for understanding of the complex coupling between the ionisation and conformation in flexible polyampholytes, including synthetic polymers, biomimetic materials and biological molecules, such as intrinsically disordered proteins, whose function can be regulated by changes in the pH.

Expression of horse and donkey LH in COS-7 cells: evidence for low FSH activity in donkey LH compared with horse LH

1997 ◽  
Vol 152 (3) ◽  
pp. 371-377 ◽  
Author(s):  
M Chopineau ◽  
N Martinat ◽  
C Troispoux ◽  
H Marichatou ◽  
Y Combarnous ◽  
...  
Keyword(s):  
Amino Acid ◽  
Luteinizing Hormone ◽  
Amino Acid Sequence ◽  
Leydig Cell ◽  
Equus Caballus ◽  
Chorionic Gonadotrophin ◽  
Fsh Receptor ◽  
Peptide Backbone ◽  
Equus Asinus ◽  
First Time

Horse (Equus caballus) luteinizing hormone (eLH) and chorionic gonadotrophin (eCG), which have the same amino acid sequence, are unusual in that, although they express only LH activity in equids, they express dual LH and FSH activities in all other species tested. Donkey (Equus asinus) LH (dkLH) and CG (dkCG), which also share an identical peptide backbone, have been less well characterized and conflicting results concerning their FSH activity in heterologous species have appeared in the literature. In order to assess and compare the intrinsic LH and FSH activities of the horse and donkey LHs in heterologous species, recombinant eLH (r.eLH/CG) and recombinant dkLH (r.dkLH/CG) were expressed, for the first time, in COS-7 cells. Their LH activities were assessed in a rat Leydig cell bioassay, and their FSH activities were estimated in a bioassay using Y1 cells stably expressing the human FSH receptor. Human CG (hCG) was expressed (r.hCG) and analysed in the same system. The results showed that, whereas r.dkLH/CG was about twice as active as r.eLH/CG in the LH bioassay, it was five times less active than r.eLH/CG in the FSH bioassay; r.hCG was about three times less active than r.eLH/CG in the LH bioassay but was completely inactive in the FSH bioassay. These results confirm that dkLH/CG possesses significant FSH activity in heterologous species that is not attributable to contamination with FSH. Journal of Endocrinology (1997) 152, 371–377

Sign in / Sign up

Export Citation Format

Share Document