Determination of hydrogen exchange and relaxation parameters in PHIP complexes at micromolar concentrations

Abstract. Non-hydrogenative para-hydrogen-induced polarization (PHIP) is a fast, efficient and relatively inexpensive approach to enhance nuclear magnetic resonance (NMR) signals of small molecules in solution. The efficiency of this technique depends on the interplay of NMR relaxation and kinetic processes, which, at high concentrations, can be characterized by selective inversion experiments. However, in the case of dilute solutions this approach is clearly not viable. Here, we present alternative PHIP-based NMR experiments to determine hydrogen and hydride relaxation parameters as well as the rate constants for para-hydrogen association with and dissociation from asymmetric PHIP complexes at micromolar concentrations. Access to these parameters is necessary to understand and improve the PHIP enhancements of (dilute) substrates present in, for instance, biofluids and natural extracts.

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Determination of hydrogen exchange and relaxation parameters in PHIP complexes at micromolar concentrations

10.5194/mr-2021-23 ◽

2021 ◽

Author(s):

Lisanne Sellies ◽

Ruud L. E. G. Aspers ◽

Marco Tessari

Keyword(s):

Small Molecules ◽

Hydrogen Exchange ◽

Nmr Relaxation ◽

Para Hydrogen ◽

Natural Extracts ◽

Relaxation Parameters ◽

Selective Inversion ◽

High Concentrations ◽

Nmr Signals

Abstract. Non-hydrogenative Para-Hydrogen Induced Polarization (PHIP) is a fast, efficient and relatively inexpensive approach to enhance Nuclear Magnetic Resonance (NMR) signals of small molecules in solution. The efficiency of this technique depends on the interplay of NMR relaxation and kinetic processes, which, at high concentrations, can be characterized by selective inversion experiments. However, in the case of dilute solutions this approach is clearly not viable. Here, we present alternative PHIP-based NMR experiments to determine hydrogen and hydrides’ relaxation parameters as well as the rate constants for p-H2 association and dissociation from asymmetric PHIP complexes at micromolar concentrations. Access to these parameters is necessary to understand and improve the PHIP enhancements of (dilute) substrates present in, for instance, biofluids and natural extracts.

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Determination of backbone dynamics of (Pro-Hyp-Gly)10 and a designed collagen-like triple-helical peptide by nitrogen-15 NMR relaxation and hydrogen-exchange measurements

Biochemistry ◽

10.1021/bi00211a043 ◽

1993 ◽

Vol 32 (48) ◽

pp. 13299-13309 ◽

Cited By ~ 71

Author(s):

Pei Fan ◽

Ming Hua Li ◽

Barbara Brodsky ◽

Jean Baum

Keyword(s):

Hydrogen Exchange ◽

Nmr Relaxation ◽

Backbone Dynamics ◽

Helical Peptide

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Methods for the Determination of the Purity of Exosomes

Current Pharmaceutical Design ◽

10.2174/1381612825666191206162712 ◽

2020 ◽

Vol 25 (42) ◽

pp. 4464-4485 ◽

Cited By ~ 4

Author(s):

Katarzyna Kluszczyńska ◽

Liliana Czernek ◽

Wojciech Cypryk ◽

Łukasz Pęczek ◽

Markus Düchler

Keyword(s):

Drug Transport ◽

Biological Fluids ◽

Drug Carriers ◽

Biological Functions ◽

Isolation And Purification ◽

Pubmed Database ◽

High Concentrations ◽

Targeted Release

Background: Exosomes open exciting new opportunities for advanced drug transport and targeted release. Furthermore, exosomes may be used for vaccination, immunosuppression or wound healing. To fully utilize their potential as drug carriers or immune-modulatory agents, the optimal purity of exosome preparations is of crucial importance. Methods: Articles describing the isolation and purification of exosomes were retrieved from the PubMed database. Results: Exosomes are often separated from biological fluids containing high concentrations of proteins, lipids and other molecules that keep vesicle purification challenging. A great number of purification protocols have been published, however, their outcome is difficult to compare because the assessment of purity has not been standardized. In this review, we first give an overview of the generation and composition of exosomes, as well as their multifaceted biological functions that stimulated various medical applications. Finally, we describe various methods that have been used to purify small vesicles and to assess the purity of exosome preparations and critically compare the quality of these evaluation protocols. Conclusion: Combinations of various techniques have to be applied to reach the required purity and quality control of exosome preparations.

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Identification of N-Substituted Triazolo-azetidines as Novel Antibacterials using pDualrep2 HTS Platform

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207322666190412165316 ◽

2019 ◽

Vol 22 (5) ◽

pp. 346-354

Author(s):

Yan A. Ivanenkov ◽

Renat S. Yamidanov ◽

Ilya A. Osterman ◽

Petr V. Sergiev ◽

Vladimir A. Aladinskiy ◽

...

Keyword(s):

Antibacterial Activity ◽

Large Scale ◽

Underlying Mechanism ◽

Luciferase Assay ◽

Reporter System ◽

E Coli ◽

Starting Point ◽

High Concentrations ◽

Mic Value

Aim and Objective: Antibiotic resistance is a serious constraint to the development of new effective antibacterials. Therefore, the discovery of the new antibacterials remains one of the main challenges in modern medicinal chemistry. This study was undertaken to identify novel molecules with antibacterial activity. Materials and Methods: Using our unique double-reporter system, in-house large-scale HTS campaign was conducted for the identification of antibacterial potency of small-molecule compounds. The construction allows us to visually assess the underlying mechanism of action. After the initial HTS and rescreen procedure, luciferase assay, C14-test, determination of MIC value and PrestoBlue test were carried out. Results: HTS rounds and rescreen campaign have revealed the antibacterial activity of a series of Nsubstituted triazolo-azetidines and their isosteric derivatives that has not been reported previously. Primary hit-molecule demonstrated a MIC value of 12.5 µg/mL against E. coli Δ tolC with signs of translation blockage and no SOS-response. Translation inhibition (26%, luciferase assay) was achieved at high concentrations up to 160 µg/mL, while no activity was found using C14-test. The compound did not demonstrate cytotoxicity in the PrestoBlue assay against a panel of eukaryotic cells. Within a series of direct structural analogues bearing the same or bioisosteric scaffold, compound 2 was found to have an improved antibacterial potency (MIC=6.25 µg/mL) close to Erythromycin (MIC=2.5-5 µg/mL) against the same strain. In contrast to the parent hit, this compound was more active and selective, and provided a robust IP position. Conclusion: N-substituted triazolo-azetidine scaffold may be used as a versatile starting point for the development of novel active and selective antibacterial compounds.

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Electroanalytical Techniques for the Detection of Selenium as a Biologically and Environmentally Significant Analyte—A Short Review

Molecules ◽

10.3390/molecules26061768 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1768

Author(s):

Miroslav Rievaj ◽

Eva Culková ◽

Damiána Šandorová ◽

Zuzana Lukáčová-Chomisteková ◽

Renata Bellová ◽

...

Keyword(s):

Oxidative Stress ◽

Essential Element ◽

Analytical Techniques ◽

High Sensitivity ◽

Stripping Voltammetry ◽

Short Review ◽

Electroanalytical Methods ◽

High Concentrations ◽

Speed Of Analysis

This short review deals with the properties and significance of the determination of selenium, which is in trace amounts an essential element for animals and humans, but toxic at high concentrations. It may cause oxidative stress in cells, which leads to the chronic disease called selenosis. Several analytical techniques have been developed for its detection, but electroanalytical methods are advantageous due to simple sample preparation, speed of analysis and high sensitivity of measurements, especially in the case of stripping voltammetry very low detection limits even in picomoles per liter can be reached. A variety of working electrodes based on mercury, carbon, silver, platinum and gold materials were applied to the analysis of selenium in various samples. Only selenium in oxidation state + IV is electroactive therefore the most of voltammetric determinations are devoted to it. However, it is possible to detect also other forms of selenium by indirect electrochemistry approach.

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The Double Face of Ketamine—The Possibility of Its Identification in Blood and Beverages

Molecules ◽

10.3390/molecules26040813 ◽

2021 ◽

Vol 26 (4) ◽

pp. 813

Author(s):

Magdalena Świądro ◽

Paweł Stelmaszczyk ◽

Irena Lenart ◽

Renata Wietecha-Posłuszny

Keyword(s):

Date Rape ◽

Signal To Noise Ratio ◽

High Sensitivity ◽

Heroin Addiction ◽

Assisted Extraction ◽

Low Concentrations ◽

High Concentrations ◽

Rosé Wine ◽

Tof Ms

The purpose of this study was to develop and validate a high-sensitivity methodology for identifying one of the most used drugs—ketamine. Ketamine is used medicinally to treat depression, alcoholism, and heroin addiction. Moreover, ketamine is the main ingredient used in so-called “date-rape” pills (DRP). This study presents a novel methodology for the simultaneous determination of ketamine based on the Dried Blood Spot (DBS) method, in combination with capillary electrophoresis coupled with a mass spectrometer (CE-TOF-MS). Then, 6-mm circles were punched out from DBS collected on Whatman DMPK-C paper and extracted using microwave-assisted extraction (MAE). The assay was linear in the range of 25–300 ng/mL. Values of limits of detection (LOD = 6.0 ng/mL) and quantification (LOQ = 19.8 ng/mL) were determined based on the signal to noise ratio. Intra-day precision at each determined concentration level was in the range of 6.1–11.1%, and inter-day between 7.9–13.1%. The obtained precision was under 15.0% (for medium and high concentrations) and lower than 20.0% (for low concentrations), which are in accordance with acceptance criteria. Therefore, the DBS/MAE/CE-TOF-MS method was successfully checked for analysis of ketamine in matrices other than blood, i.e., rose wine and orange juice. Moreover, it is possible to identify ketamine in the presence of flunitrazepam, which is the other most popular ingredient used in DRP. Based on this information, the selectivity of the proposed methodology for identifying ketamine in the presence of other components of rape pills was checked.

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Error Detection of High Concentrations of Endogenous Free Glycerol in Determination of Serum Triglyceride with the TBA-80S Automated Discrete Analyzer

Clinical Chemistry ◽

10.1093/clinchem/38.7.1376a ◽

1992 ◽

Vol 38 (7) ◽

pp. 1376-1377

Author(s):

I Maeda ◽

S Hayashi ◽

R Fushimi ◽

N Amino ◽

K Miyai

Keyword(s):

Error Detection ◽

Serum Triglyceride ◽

Free Glycerol ◽

High Concentrations

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Effects of Macronutrients in the Physiological Quality of Soybean Seeds

Journal of Agricultural Science ◽

10.5539/jas.v10n5p312 ◽

2018 ◽

Vol 10 (5) ◽

pp. 312

Author(s):

Geliandro Anhaia Rigo ◽

Luis Osmar Braga Schuch ◽

Willian Silva Barros ◽

Rodrigo Lamaison de Vargas ◽

Vinícius Jardel Szareski ◽

...

Keyword(s):

Graduate Program ◽

Plant Tissues ◽

Soybean Seeds ◽

Rio Grande Do Sul ◽

Genetic Characteristics ◽

Physiological Quality ◽

High Concentrations ◽

Nitrogen Phosphorus

The aim of this work was to correlate macronutrient content of soybean seeds to physiological quality of different cultivars. The work was developed in the Federal University of Pelotas, in the facilities of the Seed Science and Technology Graduate Program. The experimental design was randomized blocks in arranged in four replicates. The following soybean cultivars were used: BMX Apolo RR (12 lots), BMX Ativa RR (13 lots), BMX Energia RR (26 lots), BMX Força RR (24 lots), BMX Impacto RR (35 lots), BMX Magna RR (16 lots), BMX Turbo RR (44 lots), BMX Potência RR (82 lots) and NA 5909 RR (28 lots), with seeds produced in northwest Rio Grande do Sul. The determination of nutritional contents found in plant tissues of soybean seeds, were measured: Nitrogen (N), Phosphorus (P), Potassium (K), Magnesium (Mg), Calcium (Ca), Sulfur (S). The macronutrient contents of the seeds vary according to genetic characteristics of the cultivars, with higher oscillations of nitrogen, phosphorus, magnesium and sulfur contents present in soybean seeds. Potassium and calcium are defined as the most stable nutrients for the cultivars and seed lots analyzed. High concentrations of nitrogen, phosphorus and calcium are determinants for the physiological quality of soybean seeds.

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