New mono- and difunctionalized 2,2,5,5-tetramethylpyrrolidine- and Δ3-pyrroline-1-oxyl nitroxide spin labels

1982 ◽  
Vol 60 (12) ◽  
pp. 1439-1447 ◽  
Author(s):  
John F. W. Keana ◽  
Kálmán Hideg ◽  
G. Bruce Birrell ◽  
Olga H. Hankovszky ◽  
George Ferguson ◽  
...  
Keyword(s):  
Alkylating Agent ◽  
Conjugate Addition ◽  
Crystallographic Analysis ◽  
Water Soluble ◽  
Covalent Attachment ◽  
Spin Labels ◽  
Phenacyl Bromide ◽  
Trans Isomers ◽  
Nitroxide Spin Labels ◽  
Mobile Component

Several new nitroxide spin labels have been prepared. Nitroxide mesylate 5 and p-hydroxyacetophenone gave 6 which was selectively brominated with cupric bromide to give the alkylating agent 7. The more water soluble phenacyl bromide analogue 17 was prepared either via the route 8 → 11 → 17 or else via the route 15 → 16 → 11 → 17. Preliminary results indicate that toward aconitase, nitroxide alkylating agent 17 behaves similarly to phenacyl bromide. Several new difunctional nitroxides were prepared with an eye toward application as saturation transfer esr spin labels. Conjugate addition of HCN to 11 gave 18, condensation of which with p-azidobenzaldehyde gave photolabile 19. Azide 20 could similarly be prepared directly from 11. Aldehyde 15 underwent condensation with p-azidoacetophenone to give azide 21. This substance was allowed to react with hemoglobin. Upon photolysis the esr spectral mobile component was substantially reduced, suggesting covalent attachment at more than one site. Conjugate addition of HCN to 23 gave a mixture of cis, trans isomers 24 and 25; the structure of 25 was established by X-ray crystallographic analysis to be the trans isomer. Conjugate addition of ethyl thioglycolate to 15 led to heterocycles 29–34.

Some chemical and analytical aspects of polysaccharide modifications. IV. Electron spin resonance studies of nitroxide-labelled chitin and chitosan derivatives

1984 ◽  
Vol 62 (5) ◽  
pp. 975-980 ◽  
Author(s):  
Manssur Yalpani ◽  
Laurance D. Hall
Keyword(s):  
Spin Label ◽  
Water Soluble ◽  
Spin Labels ◽  
Chitosan Derivatives ◽  
Terminal Galactose ◽  
Spin Resonance ◽  
Nitroxide Spin Labels ◽  
Covalently Linked ◽  
Chitin And Chitosan ◽  
Probe Spin

Nitroxide spin labels have been attached to chitin, chitosan, and their derivatives in order to investigate the solution and gel characteristics of these polymers. Thus, chitin was nonselectively acylated using the chloroacetamide label 3 to afford. the corresponding nitroxide derivative 4. Selective and nonselective labelling of chitosan was accomplished either via reductive alkylation using the keto label 5 and sodium cyanoborohydride or via a chitosan sulfate intermediate using labels 3 or 5. Two branched water soluble chitosan derivatives, carrying C-6 oxidized, terminal galactose side chains were selectively labelled by reductive animation using the amine label 13 to yield derivatives 14 and 15. Motional correlation values of the covalently-linked nitroxide moieties were shown to reflect the nature of the linkage between spin label and polymer, as well as structural differences between the branch residues of derivatives 14 and 15. The spin-probe – spin-label method was employed to demonstrate structural heterogeneities for the chitosan derivatives 7 and 15.

scholarly journals DEER and RIDME Measurements of the Nitroxide-Spin Labelled Copper-Bound Amine Oxidase Homodimer from Arthrobacter Globiformis

2021 ◽  
Author(s):  
Hannah Russell ◽  
Rachel Stewart ◽  
Christopher Prior ◽  
Vasily S. Oganesyan ◽  
Thembaninkosi G. Gaule ◽  
...  
Keyword(s):  
Dipolar Coupling ◽  
Amine Oxidase ◽  
Spin Labels ◽  
Arthrobacter Globiformis ◽  
Copper Amine Oxidase ◽  
Dipole Interactions ◽  
Nitroxide Spin Labels ◽  
Double Electron Electron Resonance ◽  
Dipolar Modulation ◽  
Paramagnetic Centres

AbstractIn the study of biological structures, pulse dipolar spectroscopy (PDS) is used to elucidate spin–spin distances at nanometre-scale by measuring dipole–dipole interactions between paramagnetic centres. The PDS methods of Double Electron Electron Resonance (DEER) and Relaxation Induced Dipolar Modulation Enhancement (RIDME) are employed, and their results compared, for the measurement of the dipolar coupling between nitroxide spin labels and copper-II (Cu(II)) paramagnetic centres within the copper amine oxidase from Arthrobacter globiformis (AGAO). The distance distribution results obtained indicate that two distinct distances can be measured, with the longer of these at c.a. 5 nm. Conditions for optimising the RIDME experiment such that it may outperform DEER for these long distances are discussed. Modelling methods are used to show that the distances obtained after data analysis are consistent with the structure of AGAO.

scholarly journals Synthesis of a thermoresponsive crosslinked MEO2MA polymer coating on microclusters of iron oxide nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alejandro Lapresta-Fernández ◽  
Alfonso Salinas-Castillo ◽  
Luis Fermín Capitán-Vallvey
Keyword(s):  
Iron Oxide ◽  
Synthesis Temperature ◽  
Water Soluble ◽  
Covalent Attachment ◽  
Solution Temperature ◽  
Tetraethylene Glycol ◽  
Critical Solution Temperature ◽  
Large Size ◽  
Transmission Electron ◽  
Azo Initiator

AbstractEncapsulation of magnetic nanoparticles (MNPs) of iron (II, III) oxide (Fe3O4) with a thermopolymeric shell of a crosslinked poly(2-(2-methoxyethoxy)ethyl methacrylate) P(MEO2MA) is successfully developed. Magnetic aggregates of large size, around 150–200 nm are obtained during the functionalization of the iron oxide NPs with vinyl groups by using 3-butenoic acid in the presence of a water soluble azo-initiator and a surfactant, at 70 °C. These polymerizable groups provide a covalent attachment of the P(MEO2MA) shell on the surface of the MNPs while a crosslinked network is achieved by including tetraethylene glycol dimethacrylate in the precipitation polymerization synthesis. Temperature control is used to modulate the swelling-to-collapse transition volume until a maximum of around 21:1 ratio between the expanded: shrunk states (from 364 to 144 nm in diameter) between 9 and 49 °C. The hybrid Fe3O4@P(MEO2MA) microgel exhibits a lower critical solution temperature of 21.9 °C below the corresponding value for P(MEO2MA) (bulk, 26 °C). The MEO2MA coating performance in the hybrid microgel is characterized by dynamic light scattering and transmission electron microscopy. The content of preformed MNPs [up to 30.2 (wt%) vs. microgel] was established by thermogravimetric analysis while magnetic properties by vibrating sample magnetometry.

Comparison of Ionic and Non-Ionic Nitroxide Spin Labels for Urographic Enhancement in Magnetic Resonance Imaging

1987 ◽  
Vol 28 (5) ◽  
pp. 593-600 ◽  
Author(s):  
Wolfgang Grodd ◽  
H. Paajanen ◽  
U. G. Eriksson ◽  
D. Revel ◽  
F. Terrier ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Spin Labels ◽  
Resonance Imaging ◽  
Nitroxide Spin Labels
Sign in / Sign up

Export Citation Format

Share Document