1H N.M.R. investigations of the selective intramolecular migration of a platinum(II) complex from methionine sulfur to imidazole N 1 in N-acetylated L-methionyl-L-histidine

2000 ◽  
Vol 53 (8) ◽  
pp. 645 ◽  
Author(s):  
Milo I. Djuran ◽  
Snezana U. Milinkovic´
Keyword(s):  
Nitrogen Atom ◽  
Sulfur Atom ◽  
Phosphate Buffer ◽  
Room Temperature ◽  
Imidazole Ring ◽  
Covalent Modification ◽  
Side Chain ◽  
Peptide Complex ◽  
Methionine Residue ◽  
Sulfur Bond

Reactions of two platinum(II) complexes [Pt(dien)Cl]+ and [Pt(Gly-Met-S,N,N´)Cl], in which dien is diethylenetriamine and Gly-Met is the dipeptide glycyl-L-methionine coordinated through the sulfur and two nitrogen atoms, with N-acetylated dipeptide L-methionyl-L-histidine (MeCO-Met-His) have been studied by 1H n.m.r. spectroscopy. All reactions were carried out in 50 mM phosphate buffer at pD 7.4 and at room temperature. In the initial stages of the reactions both platinum(II) complexes form a kinetically favoured platinum–peptide complex with unidentate coordination of MeCO-Met-His through the sulfur atom of the methionine residue. In the second stages of the reaction an intramolecular migration of a [Pt(dien)]2+ unit from the sulfur to the nitrogen atom of imidazole has been observed. This migration reaction is very slow and strongly selective to the N 1 atom of the imidazole ring of the histidine side chain. No migration of the platinum(II) complex was observed in the reaction between [Pt(Gly-Met-S,N,N´)Cl] and the dipeptide MeCO-Met-His. It was found that the latter complex, with a more sterically hindered Gly-Met ligand, reacts more slowly with thioether-containing molecules than [Pt(dien)Cl]+ and forms a more stable platinum–sulfur bond. This study is an important step in the development of new platinum(II) complexes for selective covalent modification of peptides and proteins.

Fine structural morphology of immunocytes of some molluscs and insects

1990 ◽  
Vol 48 (3) ◽  
pp. 386-387
Author(s):  
S.G. Pal ◽  
G. Baur ◽  
B. Ghosh ◽  
S. Palit ◽  
S. Modak ◽  
...  
Keyword(s):  
Blood Cells ◽  
Phosphate Buffer ◽  
Room Temperature ◽  
Structural Information ◽  
Uranyl Acetate ◽  
Meretrix Meretrix ◽  
Lead Citrate ◽  
Bivalve Molluscs ◽  
Structural Morphology ◽  
Ultrathin Sections

In recent years some of the blood cells of several molluscs and insects are characterised as immunocytes. Similar cells from a few invertebrates from India have been looked into under conventional TEM to register the ultrastructural features. This type of study is first of its kind in the subcontinent. Immunocytes from bivalve molluscs Meretrix meretrix, Laroellidens marqinalis and two insect species, apterygote Ctenolepism a longicaudata and pterygote Gesonula punctifrons provide a new set of fine structural information which forms a basis of comparison with those studied earlier.Immunocytes have been collected from the fresh live species of bivalve molluscs and insects obtained locally at Calcutta. These were fixed in icecold 2% glutaraldehyde in 0.1M phosphate buffer (pH 7.2-7.4) for 1-2 hours at 4-5°C. Subseguently pellets were post-osmicated in 1% OsO4 at room temperature for 1-2 hours. Following dehydration these were embedded in Araldite mixture in plastic capsules and polymerization was effected for 2 days at 60°C. Ultrathin sections were cut in a ultrotome and sections were double stained with Uranyl acetate and lead citrate. These were viewed in a TEM.

Catalytic activity of CuGHK peptide-based porous material

2021 ◽  
Author(s):  
Francisco G. Cirujano ◽  
Nuria Martin ◽  
Neyvis Almora-Barrios ◽  
Carlos Martí-Gastaldo
Keyword(s):  
Catalytic Activity ◽  
Porous Material ◽  
Active Sites ◽  
Room Temperature ◽  
Side Chain ◽  
Periodic Distribution ◽  
Lysine Side Chain ◽  
One Step

Room temperature one-step synthesis of the peptide-based porous material with a periodic distribution of pockets decorated with lysine side chain active sites behaves as a heterogeneous organocatalyst. The pockets are...

13-Membered Azo- and Azoxycrown Compounds with Sulfur Atom in Long Side Chain

2000 ◽  
Vol 12 (2) ◽  
pp. 213-216 ◽  
Author(s):  
Anna Skwierawska ◽  
Jan F. Biernat ◽  
R. Bilewicz
Keyword(s):  
Sulfur Atom ◽  
Side Chain

scholarly journals Engineering Increased Stability in the Antimicrobial Peptide Pediocin PA-1

2000 ◽  
Vol 66 (11) ◽  
pp. 4798-4802 ◽  
Author(s):  
Line Johnsen ◽  
Gunnar Fimland ◽  
Vincent Eijsink ◽  
Jon Nissen-Meyer
Keyword(s):  
Antimicrobial Peptide ◽  
Molecular Mass ◽  
Room Temperature ◽  
Bacteriocin Activity ◽  
Food Preservative ◽  
Food Grade ◽  
First Order ◽  
Methionine Residue ◽  
First Order Kinetics

ABSTRACT Pediocin PA-1 is a food grade antimicrobial peptide that has been used as a food preservative. Upon storage at 4°C or room temperature, pediocin PA-1 looses activity, and there is a concomitant 16-Da increase in the molecular mass. It is shown that the loss of activity follows first-order kinetics and that the instability can be prevented by replacing the single methionine residue (Met31) in pediocin PA-1. Replacing Met by Ala, Ile, or Leu protected the peptide from oxidation and had only minor effects on bacteriocin activity (for most indicator strains 100% activity was maintained). Replacement of Met by Asp was highly deleterious for bacteriocin activity.

Spectroelectrochemical Raman Study of two α,α'-End Capped Sexithiophenes: The Effect of the Introduction of a Polarisable Sulfur Atom in the Side Chain

2000 ◽  
Vol 660 ◽  
Author(s):  
J. Casado ◽  
H. E. Katz ◽  
V. Hernández ◽  
J.T. López Navarrete
Keyword(s):  
Raman Spectra ◽  
Sulfur Atom ◽  
Theoretical Calculations ◽  
Side Chain ◽  
Atomic Charges ◽  
Raman Study ◽  
Ft Raman

ABSTRACTIn this paper, the vibrational FT-Raman spectra obtained at different anodic potentials chosen in the oxidation and reduction branches of the voltamperometric waves of two α,α'-sexithiophenes end capped with n-hexyl and n-thiohexyl groups are investigated. In order to analyze the evolution of the atomic charges and bonth lengths on going from the neutral to the doped species some theoretical calculations have been carried out.

scholarly journals Catalysis of Hydrazone and Oxime Peptide Ligation by Arginine

2020 ◽  
Author(s):  
Nathalie Ollivier ◽  
Vangelis Agouridas ◽  
Benoît Snella ◽  
Rémi Desmet ◽  
Hervé Drobecq ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Phosphate Buffer ◽  
Side Chain ◽  
Neutral Ph ◽  
Arginine Hydrochloride ◽  
Guanidinium Group ◽  
Aggregation Inhibitor ◽  
Peptide Ligation

Hydrazone and oxime peptide ligations are catalyzed by arginine. The catalysis is assisted intramolecularly by the side-chain guanidinium group. Hydrazone ligation in the presence of arginine proceeds efficiently in phosphate buffer at neutral pH but is particularly powerful in bicarbonate/CO<sub>2</sub> buffer. In addition to acting as a catalyst, arginine prevents the aggregation of proteins during ligation. With its dual properties as nucleophilic catalyst and protein aggregation inhibitor, arginine hydrochloride is a useful addition to the hydrazone/oxime ligation toolbox.<br>

An Efficient Two-Step Protocol for the Isoprenylation of Xanthone at the C2 Position Starting from 1-Fluoroxanthone Derivative

Synlett ◽  
2020 ◽  
Vol 31 (14) ◽  
pp. 1423-1429
Author(s):  
Takashi Matsumoto ◽  
Yuuki Fujimoto ◽  
Chisato Furukawa ◽  
Kanae Takahashi ◽  
Miho Mochizuki ◽  
...  
Keyword(s):  
Silica Gel ◽  
Room Temperature ◽  
Claisen Rearrangement ◽  
High Yield ◽  
Side Chain ◽  
Snar Reaction

The SNAr reaction of 1-fluoroxanthone derivatives with alkoxide of 1,1-dimethylallyl alcohol cleanly afforded the corresponding ethers, which have thus far been unavailable. The obtained ethers underwent the Claisen rearrangement at room temperature by treatment with silica gel in toluene. This two-step protocol provides expeditious and high-yield access to xanthones possessing isoprenyl or the related allylic side chain at the C2 position.

scholarly journals Ionic Liquid Electrolytes for Safer and More Reliable Sodium Battery Systems

2020 ◽  
Vol 10 (18) ◽  
pp. 6323 ◽  
Author(s):  
Mariangela Bellusci ◽  
Elisabetta Simonetti ◽  
Massimo De Francesco ◽  
Giovanni Battista Appetecchi
Keyword(s):  
Thermal Stability ◽  
Ionic Liquid ◽  
Ionic Conductivity ◽  
Low Temperature ◽  
Room Temperature ◽  
Side Chain ◽  
Electrolyte Mixtures ◽  
Sodium Battery ◽  
Sodium Batteries ◽  
Battery Systems

Na+-conducting, binary electrolytic mixtures, based on 1-ethyl-3-methyl-imidazolium, trimethyl-butyl-ammonium, and N-alkyl-N-methyl-piperidinium ionic liquid (IL) families, were designed and investigated. The anions were selected among the per(fluoroalkylsulfonyl)imide families. Sodium bis(trifluoromethylsulfonyl)imide, NaTFSI, was selected as the salt. The NaTFSI-IL electrolytes, addressed to safer sodium battery systems, were studied and compared in terms of ionic conductivity and thermal stability as a function of the temperature, the nature of the anion and the cation aliphatic side chain length. Room temperature conductivities of interest for sodium batteries, i.e., largely overcoming 10−4 or 10−3 S cm−1, are displayed. Similar conduction values are exhibited by the EMI-based samples even below −10 °C, making these electrolyte mixtures potentially appealing also for low temperature applications. The NaTFSI-IL electrolytes, with the exception of the FSI-ones, are found to be thermally stable up to 275 °C, depending on the nature of the cation and/or anion, thus extending their applicability above 100 °C and remarkably increasing the reliability and safety of the final device, especially in the case of prolonged overheating.

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