Interaction of amides with strong organic acids

Purkina, A.V.; Kol'tsov, A. I.; Волчек, Б. З.

doi:10.1007/bf00607308

Cited by 7 publications

(3 citation statements)

References 12 publications

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“…The attribution is not as obvious as it might be. It could be due to traces of trifluoroacetic acid (TFA used in the production of peptide) in interaction with nonbiological amide (Purkina et al ., ) or with other protonated species (Redington & Lin, ). It is possible to remove the major part of the TFA but some traces directly in interaction with the fibres always remain.…”

Section: Resultsmentioning

confidence: 99%

Correlative infrared nanospectroscopy and transmission electron microscopy to investigate nanometric amyloid fibrils: prospects and challenges

Partouche

Mathurin

Malabirade

et al. 2019

Journal of Microscopy

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Summary Propagation of structural information through conformational changes in host‐encoded amyloid proteins is at the root of many neurodegenerative disorders. Although important breakthroughs have been made in the field, fundamental issues like the 3D‐structures of the fibrils involved in some of those disorders are still to be elucidated. To better characterise those nanometric fibrils, a broad range of techniques is currently available. Nevertheless none of them is able to perform direct chemical characterisation of single protein fibrils. In this work, we propose to investigate the structure of the C‐terminal region of a bacterial protein called Hfq as a model amyloidogenic protein, using a correlative approach. The complementary techniques used are transmission electron microscopy and a newly developed infrared nanospectroscopy technique called AFM‐IR. We introduce and discuss the strategy that we have implemented as well as the protocol, challenges and difficulties encountered during this study to characterise amyloid assemblies at the nearly single‐molecule level. Lay Description Propagation of structural information through conformational changes in amyloid proteins is at the root of many neurodegenerative disorders. Amyloids are nanostructures originating from the aggregation of multiple copies of peptide or protein monomers that eventually form fibrils. Often described as being the cause for the development of various diseases, amyloid fibrils are of major significance in the public health domain. While important breakthroughs have been made in the field, fundamental issues like the 3D‐structures of the fibrils implied in some of those disorders are still to be elucidated. To better characterise these fibrils, a broad range of techniques is currently available for the detection and visualisation of amyloid nanostructures. Nevertheless none of them is able to perform direct chemical characterisation of single protein fibrils. In this work, we propose to investigate the structure of model amyloidogenic fibrils using a correlative approach. The complementary techniques used are transmission electron microscopy and a newly developed infrared nanospectroscopy technique called AFM‐IR that allows chemical characterisation at the nanometric scale. The strategy, protocol, challenges and difficulties encountered in this approach are introduced and discussed herein.

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Section: Resultsmentioning

confidence: 99%

Correlative infrared nanospectroscopy and transmission electron microscopy to investigate nanometric amyloid fibrils: prospects and challenges

Partouche

Mathurin

Malabirade

et al. 2019

Journal of Microscopy

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“…The amide in lincomycin is a conjugated system (Abraham and Smith, 1988), resulting in potential protonation of the acyl oxygen and a net positive charge (Fig. 3) at the amine nitrogen (Purkina et al, 1971). The second location for protonation is the nitrogen in the pyrrolidine ring (Khamidullina et al, 2005).…”

Section: Resultsmentioning

confidence: 99%

Sorption/Desorption of Lincomycin from Three Arid-Region Soils

et al. 2013

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The antibiotic lincomycin is commonly found in treated municipal waste water and in waste from swine and poultry production. Environmental disposal of these wastes has the potential to introduce a significant mass of lincomycin into the ecosystem. In the present study, a series of sorption and desorption experiments were conducted to determine the potential mobility of lincomycin in soils from arid environments. Sorption and desorption isotherms were obtained for lincomycin using three different soils. Isotherms were fit to the Freundlich equation. Adsorption of lincomycin was found to have a of 11.98 for a biosolid-treated soil (1.58% OC) and a of 210.15 for a similar unamended soil (1.42% OC). It was also found that for a low-organic-content soil the was 5.09. The differences in adsorption can be related to the soil pH and the pKa of lincomycin (7.5-7.8). When the soil solution pH is below the pKa, the cationic species of lincomycin dominates, resulting in increased water solubility. Interaction with the cation exchange complex is minimal due to a high solution cation concentration (Ca and Na). Desorption isotherms also indicate that when the solution pH is lower than the pKa, retention of lincomycin is reduced. Our results indicate that the mobility of lincomycin in these arid region soils is dependent on soil pH.

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“…Under quiet similar galvanostatic conditions, N-alkyl and N,N-dialkyl phenylacetamides yielded nuclear o-fluorinated compound as the predominant products (Table 5 and 9). In Et 3 N Á 4HF medium it appears that acetamides undergo facile protonation [30,31].…”

Section: Cyclic Voltammetry and Potentiostatic Electrolysismentioning

confidence: 97%