The effect of P-chiral center on helical conformation of optically active N-propargylphosphonamidates

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Lihua Lu ◽  
Jiaoli Mo ◽  
Qiang Yang ◽  
Liqun Zhang ◽  
Weimin Wang ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
31P Nmr ◽  
Helical Structure ◽  
Cd Spectroscopy ◽  
Optically Active ◽  
The Other ◽  
Chiral Center ◽  
Single Peak ◽  
Helical Conformation ◽  
Molecular Weights

AbstractNovel chiral and achiral N-propargylphosphonamidate monomers [HC=CCH2NH(P=O)R1R2,where 1: R1=CH3,R2=NHC(CH3)32: R1=CH3,R2 =NHC5H93:R1=OPh,R2=NHC(CH3)3, 4:R1=R2=OPh] were synthesized by successive condensation in order to study the helical conformation properties of N-phosphonamidates. One diastereomer was successfully separated from the other in the cases of monomer 1-3(named 1a-3a) according to the single peak in the 31P NMR spectra. Polymerizations of the monomers 1-4 were carried out with (nbd)Rh+[η6-C6H5B-(C6H5)3] as catalyst in CHCl3 yielding the polymers with number-average molecular weights of 1300-22400. Poly(1a)-poly(3a) and poly(4) were characterized by UV and CD spectroscopy. Poly(1a)- poly(3a) showed an intense positive CD signal at 325 nm based on the conjugated polyacetylene backbone while poly(4) showed no peak there, indicating that the polymers had a helical structure with predominantly one-handed screw sense because of P-chiral centre sole contribution.

Hyperthermia Induced Polyphosphate Changes in Propionibacterium acnes as Studied by 31P NMR

1989 ◽  
Vol 44 (1-2) ◽  
pp. 45-48 ◽  
Author(s):  
B. Kjeldstad ◽  
A . Johnsson ◽  
K. M. Furuheim ◽  
A . Schie Bergan ◽  
J. Krane
Keyword(s):  
Nmr Spectra ◽  
31P Nmr ◽  
Propionibacterium Acnes ◽  
Ultra Violet ◽  
The Other ◽  
Hyperthermia Treatment ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Increasing Temperature ◽  
Induced Changes

Abstract The polyphosphate component in MP NMR spectra of the Gram-positive Propionibacterium acnes increased after hyperthermia treatment. The cells were exposed to temperatures in the interval from 15 °C to 45 °C. The amount of polyphosphate increased with increasing temperature. There were no temperature induced changes in the other phosphorous components seen in the spectra with exception of a decrease in ATP for higher temperatures. The increase in polyphosphates was less than that obtained from cells irradiated by near ultra-violet light.

The structure of the rodent and porcine neuropeptide galanin and antagonists as determined by FTIR and CD spectroscopy

1994 ◽  
Vol 72 (6) ◽  
pp. 1495-1499 ◽  
Author(s):  
Anders B.A. Wennerberg ◽  
Michael Jackson ◽  
Anders Öhman ◽  
Astrid Gräslund ◽  
Ülo Langel ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Ir Spectroscopy ◽  
Helical Structure ◽  
Cd Spectroscopy ◽  
Helical Conformation ◽  
Sds Micelles ◽  
Zwitterionic Lipids ◽  
Ft Ir ◽  
Solvent Systems ◽  
Ft Ir Spectroscopy

FT-IR spectroscopy was used to study the conformation of the porcine neuropeptide galanin, fragments 1−16 of the porcine and human peptides and the antagonists M15 and M35. All peptides were shown to be structureless in aqueous solution. Upon addition to SDS micelles, only porcine galanin and the fragment consisting of amino acids 1−16 showed any evidence of interaction, adopting a helical structure. No interaction could be demonstrated with zwitterionic lipids for any peptide except M15 which formed a thermally unstable helical conformation which unfolded promoting aggregation at around 45 °C.Additional studies on rat galanin in various solvent systems were made by using circular dichroism spectroscopy. The results obtained support the observations made by FT-IR spectroscopy.

The Electron Effect of Aromatic Group: Control Conformation of 2-Aromatic Cyclododecanone Derivatives

2020 ◽  
Vol 24 (10) ◽  
pp. 1139-1147
Author(s):  
Yang Mingyan ◽  
Wang Daoquan ◽  
Wang Mingan
Keyword(s):  
1H Nmr ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
The Other ◽  
Repulsive Interaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Effect ◽  
Group Control

2-Phenylcyclododecanone and 2-cyclohexylcyclododecanone derivatives were synthesized and characterized by 1H NMR, 13C NMR, HR-ESI-MS and X-ray diffraction. Their preferred conformations were analyzed by the coupling constants in the 1H NMR spectra and X-ray diffraction, which showed the skeleton ring of these derivatives containing [3333]-2-one conformation, and the phenyl groups were located at the side-exo position of [3333]-2-one conformation due to the strong π-π repulsive interaction between the π- electron of benzene ring and π-electron of carbonyl group. The cyclohexyl groups were located at the corner-syn or the side-exo position of [3333]-2-one conformation depending on the hindrance of the other substituted groups. The π-π electron effect played a crucial role in efficiently controlling the preferred conformation of 2-aromatic cyclododecanone and the other 2-aromatic macrocyclic derivatives with the similar preferred square and rectangular conformations.

17O and 13C NMR spectra of some geminal diacetates

1988 ◽  
Vol 53 (3) ◽  
pp. 588-592 ◽  
Author(s):  
Antonín Lyčka ◽  
Josef Jirman ◽  
Jaroslav Holeček
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
The Other ◽  
13C Nmr Spectra ◽  
Other Hand ◽  
Carboxylic Esters ◽  
C Nmr ◽  
Oxygen Atoms

The 17O and 13C NMR spectra of eight geminal diacetates RCH(O(CO)CH3)2 derived from simple aldehydes have been measured. In contrast to the dicarboxylates R1R2E(O(CO)R3)2, where E = Si, Ge, or Sn, whose 17O NMR spectra only contain a single signal, and, on the other hand, in accordance with organic carboxylic esters, the 17O NMR spectra of the compound group studied always exhibit two well-resolved signals with the chemical shifts δ(17O) in the regions of 183-219 ppm and 369-381 ppm for the oxygen atoms in the groups C-O and C=O, respectively.

scholarly journals Naphthalimide-Containing BP100 Leads to Higher Model Membranes Interactions and Antimicrobial Activity

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 542
Author(s):  
Gustavo Penteado Battesini Carretero ◽  
Greice Kelle Viegas Saraiva ◽  
Magali Aparecida Rodrigues ◽  
Sumika Kiyota ◽  
Marcelo Porto Bemquerer ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Biological Activities ◽  
Biological Effects ◽  
Membrane Surface ◽  
Helical Structure ◽  
Helical Conformation ◽  
Property A ◽  
Cellular Processes ◽  
Double Stranded Dna ◽  
Low Toxicity

In a large variety of organisms, antimicrobial peptides (AMPs) are primary defenses against pathogens. BP100 (KKLFKKILKYL-NH2), a short, synthetic, cationic AMP, is active against bacteria and displays low toxicity towards eukaryotic cells. BP100 acquires a α-helical conformation upon interaction with membranes and increases membrane permeability. Despite the volume of information available, the action mechanism of BP100, the selectivity of its biological effects, and possible applications are far from consensual. Our group synthesized a fluorescent BP100 analogue containing naphthalimide linked to its N-terminal end, NAPHT-BP100 (Naphthalimide-AAKKLFKKILKYL-NH2). The fluorescence properties of naphthalimides, especially their spectral sensitivity to microenvironment changes, are well established, and their biological activities against transformed cells and bacteria are known. Naphthalimide derived compounds are known to interact with DNA disturbing related processes as replication and transcription, and used as anticancer agents due to this property. A wide variety of techniques were used to demonstrate that NAPHT-BP100 bound to and permeabilized zwitterionic POPC and negatively charged POPC:POPG liposomes and, upon interaction, acquired a α-helical structure. Membrane surface high peptide/lipid ratios triggered complete permeabilization of the liposomes in a detergent-like manner. Membrane disruption was driven by charge neutralization, lipid aggregation, and bilayer destabilization. NAPHT-BP100 also interacted with double-stranded DNA, indicating that this peptide could also affect other cellular processes besides causing membrane destabilization. NAPHT-BP100 showed increased antibacterial and hemolytic activities, compared to BP100, and may constitute an efficient antimicrobial agent for dermatological use. By conjugating BP100 and naphthalimide DNA binding properties, NAPHT-BP100 bound to a large extent to the bacterial membrane and could more efficiently destabilize it. We also speculate that peptide could enter the bacteria cell and interact with its DNA in the cytoplasm.

scholarly journals Secondary structure and biophysical activity of synthetic analogues of the pulmonary surfactant polypeptide SP-C

1995 ◽  
Vol 307 (2) ◽  
pp. 535-541 ◽  
Author(s):  
J Johansson ◽  
G Nilsson ◽  
R Strömberg ◽  
B Robertson ◽  
H Jörnvall ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Pulmonary Surfactant ◽  
Transmembrane Helix ◽  
Helical Structure ◽  
Helical Conformation ◽  
Synthetic Analogues ◽  
Charged Amino Acids ◽  
Phospholipid Micelles ◽  
Helical Content ◽  
Biophysical Activity

Native pulmonary-surfactant-associated lipopolypeptide SP-C, its chemically depalmitoylated form and several synthetic analogues lacking the palmitoylcysteine residues were analysed for secondary structure in phospholipid micelles and for biophysical activity in 1,2-dipalmitoyl-sn-glycero-3- phosphocholine/phosphatidylglycerol/palmitic acid (68:22:9, by wt.). Compared with the native molecule, with the entire poly-valyl part in a known alpha-helical conformation, depalmitoylated SP-C was found to be still mainly alpha-helical, but with an approx. 20% decrease in the helical content. A synthetic hybrid polypeptide where the entire poly-valyl alpha-helical part of native SP-C had been replaced with the amino acid sequence of a transmembrane helix of bacteriorhodopsin is also predominantly alpha-helical. In contrast, synthetic SP-C analogues lacking only the palmitoyl groups, by replacement of the palmitoylcysteine residues with cysteine, phenylalanine or serine, or lacking the positively charged amino acids by replacement with alanine, are considerably less alpha-helical than both native and depalmitoylated SP-C. The data indicate that the SP-C palmitoyl groups are important for maintenance of the alpha-helical conformation in parts of the polypeptide, and that the poly-valyl alpha-helical conformation is not fully formed in synthetic SP-C polypeptides. Furthermore, the helical structure of both native and depalmitoylated SP-C in dodecylphosphocholine micelles is very resistant to thermal denaturation, exhibiting ordered structure at 90 degrees C. The alpha-helical content grossly parallels the peptide-induced acceleration of the spreading of phospholipids at an air/water interface and the increase of surface pressure. The data suggest that the alpha-helical conformation itself, rather than just the covalent structure, is of prime importance for the biological function of synthetic pulmonary-surfactant peptides.

scholarly journals OSMOTIC PRESSURE STUDY OF PROTEIN FRACTIONS IN NORMAL AND IN NEPHROTIC SUBJECTS

1939 ◽  
Vol 69 (6) ◽  
pp. 819-831 ◽  
Author(s):  
Jaques Bourdillon
Keyword(s):  
Osmotic Pressure ◽  
Normal Serum ◽  
The Other ◽  
Protein Fractions ◽  
Molecular Weights ◽  
Other Hand ◽  
Normal Albumin

In serum of patients with nephrosis both albumin and globulin showed by osmotic pressure nearly double the molecular weights of normal albumin and globulin. In the urines of such patients, on the other hand, both proteins showed molecular weights lower even than in normal serum. The colloidal osmotic pressures were measured by the author's method at such dilutions that the van't Hoff law relating pressures to molecular concentrations could be directly applied. For the albumin and globulin of normal serum the molecular weights found were 72,000 and 164,000 respectively, in agreement with the weights obtained by other methods.

THE EXTRACTION OF ORGANIC MATTER FROM SELECTED SOILS AND PARTICLE SIZE FRACTIONS WITH 0.5 M NaOH AND 0.1 M Na4P2O7 SOLUTIONS

1989 ◽  
Vol 69 (2) ◽  
pp. 253-262 ◽  
Author(s):  
M. SCHNITZER ◽  
P. SCHUPPLI
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Acids ◽  
Nmr Spectra ◽  
Attractive Alternative ◽  
Particle Size Fractions ◽  
Molecular Weights ◽  
Naoh Solution ◽  
C Nmr ◽  
Medium Silt

Organic matter (OM) in the Bainsville and Melfort soils, and in coarse clay and medium silt fractions separated from these soils, was extracted under N2 with 0.5 M NaOH and unadjusted 0.1 M Na4P2O7 solutions. pH ranges of the soils and fractions in contact for 24 h with 0.5 M NaOH and 0.1 M Na4P2O7 solutions extended from 12.2 to 12.6 and 9.0 to 9.4, respectively. Slightly greater proportions of the soil-carbon were extracted by 0.5 M NaOH than by 0.1 M Na4P2O7 solution. The differences, however, did not appear to be significant and may vary from soil to soil. The efficiency of extraction and the characteristics of the extracted materials were assessed on humic acids (HAs), which were isolated from the extracts. From the Bainsville soil and fractions, 0.1 M Na4P2O7 solution extracted more high-molecular weight and more deeply colored HAs than did 0.5 M NaOH solution. But HAs extracted from the Melfort soil and fractions had similar molecular weights and colours. 13C NMR spectra showed that HAs extracted by 0.1 M Na4P2O7 solution tended to be more aromatic than HAs extracted by 0.5 M NaOH solution. Well defined solid-state 13C NMR spectra of HAs, containing up to 69.0% ash, could be recorded. Unadjusted 0.1 M Na4P2O7 solution under N2 was found to be an attractive alternative to 0.5 M NaOH solution as an extractant for soil OM. Key words: Humic acids, E4:E6 ratios, IR spectra, 13C NMR spectra, aromaticity

scholarly journals Optically active polyacetylene: Synthesis and helical conformation of a poly(phenylacetylene) carryingL-alanyl-L-alanine pendants

2005 ◽  
Vol 43 (16) ◽  
pp. 3701-3706 ◽  
Author(s):  
Lo Ming Lai ◽  
Jacky W. Y. Lam ◽  
Kevin K. L. Cheuk ◽  
Hermans H. Y. Sung ◽  
Ian D. Williams ◽  
...  
Keyword(s):  
Optically Active ◽  
Helical Conformation

Immune responses of Texel sheep to excretory/secretory products of adult Haemonchus contortus

Parasitology ◽  
1994 ◽  
Vol 108 (3) ◽  
pp. 351-357 ◽  
Author(s):  
H. D. F. H. Schallig ◽  
M. A. W. van Leeuwen ◽  
W. M. L. Hendrikx
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Haemonchus Contortus ◽  
Lymphocyte Proliferation ◽  
The Other ◽  
Proliferation Index ◽  
Serum Samples ◽  
Immunoblotting Analysis ◽  
Molecular Weights ◽  
Secretory Products

SUMMARYThe excretory/secretory (E/S) products of adult Haemonchus contortus comprise of at least 15 polypeptides with molecular weights ranging from 10 to > 100 kDa. These E/S products induce an immune response in infected Texel sheep, as demonstrated by specific IgGI levels and a significant lymphocyte proliferation index. Moreover, immunoblotting analysis revealed that sera of primary H. contortus-infected sheep specifically recognize a 24 kDa E/S product. In addition, sera of challenged sheep react strongly with a 15 kDa E/S product. The other E/S products of H. contortus showed immunoreactivity with serum samples of Haemonchus-infected sheep as well as with samples of sheep harbouring other trichostrongylid infections. These cross-reacting epitopes are the main cause of the lack of specificity of an E/S material- based ELISA. This ELISA can differentiate Haemonchus infections from Nematodirus battus infections, but not from Ostertagia circumcincta or Trichostrongylus colubriformis infections.

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